We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Cannot import name `Utc`
While trying to debug #1299 I encountered the following error:
```
$ make serve
...
~/.virtualenvs/test/bin/kinto migrate --ini config/kinto.ini
Traceback (most recent call last):
  File "~/.virtualenvs/test/bin/kinto", line 11, in <module>
    load_entry_point('kinto', 'console_scripts', 'kinto')()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 560, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2648, in load_entry_point
    return ep.load()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2302, in load
    return self.resolve()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2308, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "~/mozilla/kinto/kinto/__init__.py", line 4, in <module>
    import kinto.core
  File "~/mozilla/kinto/kinto/core/__init__.py", line 10, in <module>
    from kinto.core import errors
  File "~/mozilla/kinto/kinto/core/errors.py", line 1, in <module>
    import colander
  File "~/.virtualenvs/test/lib/python3.5/site-packages/colander/__init__.py", line 22, in <module>
    from . import iso8601
  File "~/.virtualenvs/test/lib/python3.5/site-packages/colander/iso8601.py", line 3, in <module>
    from iso8601.iso8601 import (parse_date, ParseError, Utc, FixedOffset, UTC, ZERO, ISO8601_REGEX)
ImportError: cannot import name 'Utc'
Makefile:87 : la recette pour la cible « migrate » a échouée
make: *** [migrate] Erreur 1
```
Cannot import name `Utc`
While trying to debug #1299 I encountered the following error:
```
$ make serve
...
~/.virtualenvs/test/bin/kinto migrate --ini config/kinto.ini
Traceback (most recent call last):
  File "~/.virtualenvs/test/bin/kinto", line 11, in <module>
    load_entry_point('kinto', 'console_scripts', 'kinto')()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 560, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2648, in load_entry_point
    return ep.load()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2302, in load
    return self.resolve()
  File "~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py", line 2308, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "~/mozilla/kinto/kinto/__init__.py", line 4, in <module>
    import kinto.core
  File "~/mozilla/kinto/kinto/core/__init__.py", line 10, in <module>
    from kinto.core import errors
  File "~/mozilla/kinto/kinto/core/errors.py", line 1, in <module>
    import colander
  File "~/.virtualenvs/test/lib/python3.5/site-packages/colander/__init__.py", line 22, in <module>
    from . import iso8601
  File "~/.virtualenvs/test/lib/python3.5/site-packages/colander/iso8601.py", line 3, in <module>
    from iso8601.iso8601 import (parse_date, ParseError, Utc, FixedOffset, UTC, ZERO, ISO8601_REGEX)
ImportError: cannot import name 'Utc'
Makefile:87 : la recette pour la cible « migrate » a échouée
make: *** [migrate] Erreur 1
```

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `setup.py`
Content:
```
1 import codecs
2 import os
3 from setuptools import setup, find_packages
4 
5 here = os.path.abspath(os.path.dirname(__file__))
6 
7 
8 def read_file(filename):
9     """Open a related file and return its content."""
10     with codecs.open(os.path.join(here, filename), encoding='utf-8') as f:
11         content = f.read()
12     return content
13 
14 
15 README = read_file('README.rst')
16 CHANGELOG = read_file('CHANGELOG.rst')
17 CONTRIBUTORS = read_file('CONTRIBUTORS.rst')
18 
19 REQUIREMENTS = [
20     'bcrypt',
21     'iso8601==0.1.11',  # Refs #1301
22     'colander >= 1.3.2',
23     'cornice >= 2.4',
24     'cornice_swagger >= 0.5.1',
25     'jsonschema',
26     'jsonpatch',
27     'logging-color-formatter >= 1.0.1',  # Message interpolations.
28     'python-dateutil',
29     'pyramid > 1.8, < 1.9b1',
30     'pyramid_multiauth >= 0.8',  # User on policy selected event.
31     'transaction',
32     # pyramid_tm changed the location of their tween in 2.x and one of
33     # our tests fails on 2.0.
34     'pyramid_tm >= 2.1',
35     'requests',
36     'waitress',
37     'ujson >= 1.35'
38 ]
39 
40 POSTGRESQL_REQUIRES = [
41     'SQLAlchemy',
42     'psycopg2 > 2.5',
43     'zope.sqlalchemy',
44 ]
45 
46 REDIS_REQUIRES = [
47     'kinto_redis'
48 ]
49 
50 SETUP_REQUIRES = [
51     'pytest-runner'
52 ]
53 
54 TEST_REQUIREMENTS = [
55     'bravado_core',
56     'pytest',
57     'WebTest'
58 ]
59 
60 DEPENDENCY_LINKS = [
61 ]
62 
63 MONITORING_REQUIRES = [
64     'raven',
65     'statsd',
66     'newrelic',
67     'werkzeug',
68 ]
69 
70 ENTRY_POINTS = {
71     'paste.app_factory': [
72         'main = kinto:main',
73     ],
74     'console_scripts': [
75         'kinto = kinto.__main__:main'
76     ],
77 }
78 
79 
80 setup(name='kinto',
81       version='7.3.2.dev0',
82       description='Kinto Web Service - Store, Sync, Share, and Self-Host.',
83       long_description="{}\n\n{}\n\n{}".format(README, CHANGELOG, CONTRIBUTORS),
84       license='Apache License (2.0)',
85       classifiers=[
86           "Programming Language :: Python",
87           "Programming Language :: Python :: 3",
88           "Programming Language :: Python :: 3.5",
89           "Programming Language :: Python :: 3.6",
90           "Programming Language :: Python :: Implementation :: CPython",
91           "Topic :: Internet :: WWW/HTTP",
92           "Topic :: Internet :: WWW/HTTP :: WSGI :: Application",
93           "License :: OSI Approved :: Apache Software License"
94       ],
95       keywords="web sync json storage services",
96       author='Mozilla Services',
97       author_email='storage-team@mozilla.com',
98       url='https://github.com/Kinto/kinto',
99       packages=find_packages(),
100       package_data={'': ['*.rst', '*.py', '*.yaml']},
101       include_package_data=True,
102       zip_safe=False,
103       setup_requires=SETUP_REQUIRES,
104       tests_require=TEST_REQUIREMENTS,
105       install_requires=REQUIREMENTS,
106       extras_require={
107           'redis': REDIS_REQUIRES,
108           'postgresql': POSTGRESQL_REQUIRES,
109           'monitoring': MONITORING_REQUIRES,
110       },
111       test_suite="tests",
112       dependency_links=DEPENDENCY_LINKS,
113       entry_points=ENTRY_POINTS)
114
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -18,8 +18,7 @@
 
 REQUIREMENTS = [
     'bcrypt',
-    'iso8601==0.1.11',  # Refs #1301
-    'colander >= 1.3.2',
+    'colander >= 1.4.0',
     'cornice >= 2.4',
     'cornice_swagger >= 0.5.1',
     'jsonschema',

{"golden_diff": "diff --git a/setup.py b/setup.py\n--- a/setup.py\n+++ b/setup.py\n@@ -18,8 +18,7 @@\n \n REQUIREMENTS = [\n     'bcrypt',\n-    'iso8601==0.1.11',  # Refs #1301\n-    'colander >= 1.3.2',\n+    'colander >= 1.4.0',\n     'cornice >= 2.4',\n     'cornice_swagger >= 0.5.1',\n     'jsonschema',\n", "issue": "Cannot import name `Utc`\nWhile trying to debug #1299 I encountered the following error:\r\n```\r\n$ make serve\r\n...\r\n~/.virtualenvs/test/bin/kinto migrate --ini config/kinto.ini\r\nTraceback (most recent call last):\r\n  File \"~/.virtualenvs/test/bin/kinto\", line 11, in <module>\r\n    load_entry_point('kinto', 'console_scripts', 'kinto')()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 560, in load_entry_point\r\n    return get_distribution(dist).load_entry_point(group, name)\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2648, in load_entry_point\r\n    return ep.load()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2302, in load\r\n    return self.resolve()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2308, in resolve\r\n    module = __import__(self.module_name, fromlist=['__name__'], level=0)\r\n  File \"~/mozilla/kinto/kinto/__init__.py\", line 4, in <module>\r\n    import kinto.core\r\n  File \"~/mozilla/kinto/kinto/core/__init__.py\", line 10, in <module>\r\n    from kinto.core import errors\r\n  File \"~/mozilla/kinto/kinto/core/errors.py\", line 1, in <module>\r\n    import colander\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/colander/__init__.py\", line 22, in <module>\r\n    from . import iso8601\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/colander/iso8601.py\", line 3, in <module>\r\n    from iso8601.iso8601 import (parse_date, ParseError, Utc, FixedOffset, UTC, ZERO, ISO8601_REGEX)\r\nImportError: cannot import name 'Utc'\r\nMakefile:87\u00a0: la recette pour la cible \u00ab\u00a0migrate\u00a0\u00bb a \u00e9chou\u00e9e\r\nmake: *** [migrate] Erreur 1\r\n```\nCannot import name `Utc`\nWhile trying to debug #1299 I encountered the following error:\r\n```\r\n$ make serve\r\n...\r\n~/.virtualenvs/test/bin/kinto migrate --ini config/kinto.ini\r\nTraceback (most recent call last):\r\n  File \"~/.virtualenvs/test/bin/kinto\", line 11, in <module>\r\n    load_entry_point('kinto', 'console_scripts', 'kinto')()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 560, in load_entry_point\r\n    return get_distribution(dist).load_entry_point(group, name)\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2648, in load_entry_point\r\n    return ep.load()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2302, in load\r\n    return self.resolve()\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/pkg_resources/__init__.py\", line 2308, in resolve\r\n    module = __import__(self.module_name, fromlist=['__name__'], level=0)\r\n  File \"~/mozilla/kinto/kinto/__init__.py\", line 4, in <module>\r\n    import kinto.core\r\n  File \"~/mozilla/kinto/kinto/core/__init__.py\", line 10, in <module>\r\n    from kinto.core import errors\r\n  File \"~/mozilla/kinto/kinto/core/errors.py\", line 1, in <module>\r\n    import colander\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/colander/__init__.py\", line 22, in <module>\r\n    from . import iso8601\r\n  File \"~/.virtualenvs/test/lib/python3.5/site-packages/colander/iso8601.py\", line 3, in <module>\r\n    from iso8601.iso8601 import (parse_date, ParseError, Utc, FixedOffset, UTC, ZERO, ISO8601_REGEX)\r\nImportError: cannot import name 'Utc'\r\nMakefile:87\u00a0: la recette pour la cible \u00ab\u00a0migrate\u00a0\u00bb a \u00e9chou\u00e9e\r\nmake: *** [migrate] Erreur 1\r\n```\n", "before_files": [{"content": "import codecs\nimport os\nfrom setuptools import setup, find_packages\n\nhere = os.path.abspath(os.path.dirname(__file__))\n\n\ndef read_file(filename):\n    \"\"\"Open a related file and return its content.\"\"\"\n    with codecs.open(os.path.join(here, filename), encoding='utf-8') as f:\n        content = f.read()\n    return content\n\n\nREADME = read_file('README.rst')\nCHANGELOG = read_file('CHANGELOG.rst')\nCONTRIBUTORS = read_file('CONTRIBUTORS.rst')\n\nREQUIREMENTS = [\n    'bcrypt',\n    'iso8601==0.1.11',  # Refs #1301\n    'colander >= 1.3.2',\n    'cornice >= 2.4',\n    'cornice_swagger >= 0.5.1',\n    'jsonschema',\n    'jsonpatch',\n    'logging-color-formatter >= 1.0.1',  # Message interpolations.\n    'python-dateutil',\n    'pyramid > 1.8, < 1.9b1',\n    'pyramid_multiauth >= 0.8',  # User on policy selected event.\n    'transaction',\n    # pyramid_tm changed the location of their tween in 2.x and one of\n    # our tests fails on 2.0.\n    'pyramid_tm >= 2.1',\n    'requests',\n    'waitress',\n    'ujson >= 1.35'\n]\n\nPOSTGRESQL_REQUIRES = [\n    'SQLAlchemy',\n    'psycopg2 > 2.5',\n    'zope.sqlalchemy',\n]\n\nREDIS_REQUIRES = [\n    'kinto_redis'\n]\n\nSETUP_REQUIRES = [\n    'pytest-runner'\n]\n\nTEST_REQUIREMENTS = [\n    'bravado_core',\n    'pytest',\n    'WebTest'\n]\n\nDEPENDENCY_LINKS = [\n]\n\nMONITORING_REQUIRES = [\n    'raven',\n    'statsd',\n    'newrelic',\n    'werkzeug',\n]\n\nENTRY_POINTS = {\n    'paste.app_factory': [\n        'main = kinto:main',\n    ],\n    'console_scripts': [\n        'kinto = kinto.__main__:main'\n    ],\n}\n\n\nsetup(name='kinto',\n      version='7.3.2.dev0',\n      description='Kinto Web Service - Store, Sync, Share, and Self-Host.',\n      long_description=\"{}\\n\\n{}\\n\\n{}\".format(README, CHANGELOG, CONTRIBUTORS),\n      license='Apache License (2.0)',\n      classifiers=[\n          \"Programming Language :: Python\",\n          \"Programming Language :: Python :: 3\",\n          \"Programming Language :: Python :: 3.5\",\n          \"Programming Language :: Python :: 3.6\",\n          \"Programming Language :: Python :: Implementation :: CPython\",\n          \"Topic :: Internet :: WWW/HTTP\",\n          \"Topic :: Internet :: WWW/HTTP :: WSGI :: Application\",\n          \"License :: OSI Approved :: Apache Software License\"\n      ],\n      keywords=\"web sync json storage services\",\n      author='Mozilla Services',\n      author_email='storage-team@mozilla.com',\n      url='https://github.com/Kinto/kinto',\n      packages=find_packages(),\n      package_data={'': ['*.rst', '*.py', '*.yaml']},\n      include_package_data=True,\n      zip_safe=False,\n      setup_requires=SETUP_REQUIRES,\n      tests_require=TEST_REQUIREMENTS,\n      install_requires=REQUIREMENTS,\n      extras_require={\n          'redis': REDIS_REQUIRES,\n          'postgresql': POSTGRESQL_REQUIRES,\n          'monitoring': MONITORING_REQUIRES,\n      },\n      test_suite=\"tests\",\n      dependency_links=DEPENDENCY_LINKS,\n      entry_points=ENTRY_POINTS)\n", "path": "setup.py"}], "after_files": [{"content": "import codecs\nimport os\nfrom setuptools import setup, find_packages\n\nhere = os.path.abspath(os.path.dirname(__file__))\n\n\ndef read_file(filename):\n    \"\"\"Open a related file and return its content.\"\"\"\n    with codecs.open(os.path.join(here, filename), encoding='utf-8') as f:\n        content = f.read()\n    return content\n\n\nREADME = read_file('README.rst')\nCHANGELOG = read_file('CHANGELOG.rst')\nCONTRIBUTORS = read_file('CONTRIBUTORS.rst')\n\nREQUIREMENTS = [\n    'bcrypt',\n    'colander >= 1.4.0',\n    'cornice >= 2.4',\n    'cornice_swagger >= 0.5.1',\n    'jsonschema',\n    'jsonpatch',\n    'logging-color-formatter >= 1.0.1',  # Message interpolations.\n    'python-dateutil',\n    'pyramid > 1.8, < 1.9b1',\n    'pyramid_multiauth >= 0.8',  # User on policy selected event.\n    'transaction',\n    # pyramid_tm changed the location of their tween in 2.x and one of\n    # our tests fails on 2.0.\n    'pyramid_tm >= 2.1',\n    'requests',\n    'waitress',\n    'ujson >= 1.35'\n]\n\nPOSTGRESQL_REQUIRES = [\n    'SQLAlchemy',\n    'psycopg2 > 2.5',\n    'zope.sqlalchemy',\n]\n\nREDIS_REQUIRES = [\n    'kinto_redis'\n]\n\nSETUP_REQUIRES = [\n    'pytest-runner'\n]\n\nTEST_REQUIREMENTS = [\n    'bravado_core',\n    'pytest',\n    'WebTest'\n]\n\nDEPENDENCY_LINKS = [\n]\n\nMONITORING_REQUIRES = [\n    'raven',\n    'statsd',\n    'newrelic',\n    'werkzeug',\n]\n\nENTRY_POINTS = {\n    'paste.app_factory': [\n        'main = kinto:main',\n    ],\n    'console_scripts': [\n        'kinto = kinto.__main__:main'\n    ],\n}\n\n\nsetup(name='kinto',\n      version='7.3.2.dev0',\n      description='Kinto Web Service - Store, Sync, Share, and Self-Host.',\n      long_description=\"{}\\n\\n{}\\n\\n{}\".format(README, CHANGELOG, CONTRIBUTORS),\n      license='Apache License (2.0)',\n      classifiers=[\n          \"Programming Language :: Python\",\n          \"Programming Language :: Python :: 3\",\n          \"Programming Language :: Python :: 3.5\",\n          \"Programming Language :: Python :: 3.6\",\n          \"Programming Language :: Python :: Implementation :: CPython\",\n          \"Topic :: Internet :: WWW/HTTP\",\n          \"Topic :: Internet :: WWW/HTTP :: WSGI :: Application\",\n          \"License :: OSI Approved :: Apache Software License\"\n      ],\n      keywords=\"web sync json storage services\",\n      author='Mozilla Services',\n      author_email='storage-team@mozilla.com',\n      url='https://github.com/Kinto/kinto',\n      packages=find_packages(),\n      package_data={'': ['*.rst', '*.py', '*.yaml']},\n      include_package_data=True,\n      zip_safe=False,\n      setup_requires=SETUP_REQUIRES,\n      tests_require=TEST_REQUIREMENTS,\n      install_requires=REQUIREMENTS,\n      extras_require={\n          'redis': REDIS_REQUIRES,\n          'postgresql': POSTGRESQL_REQUIRES,\n          'monitoring': MONITORING_REQUIRES,\n      },\n      test_suite=\"tests\",\n      dependency_links=DEPENDENCY_LINKS,\n      entry_points=ENTRY_POINTS)\n", "path": "setup.py"}]}