We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Error looking for icon for tutorial for 0.3.0.dev9
This is with Python 3.6.5 in a clean venv:
```
(.venv) PS C:\Users\_\Desktop\toga_tutorial> python .\helloworld.py
[Winforms] No valid icon format available for C:\Users\brcan\Desktop\toga_tutorial\.venv\lib\site-packages\toga\resources\tiberius; fall back on Tiberius instead

Unhandled Exception: Python.Runtime.PythonException: FileNotFoundException : Could not find file 'C:\Users\brcan\Desktop\toga_tutorial\.venv\lib\site-packages\toga\resources\tiberius.ico'.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at System.Drawing.Icon..ctor(String fileName, Int32 width, Int32 height)
   at Python.Runtime.Dispatcher.Dispatch(ArrayList args)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
```

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `src/core/setup.py`
Content:
```
1 #/usr/bin/env python
2 import io
3 import re
4 
5 from setuptools import setup, find_packages
6 
7 with io.open('toga/__init__.py', encoding='utf8') as version_file:
8     version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]", version_file.read(), re.M)
9     if version_match:
10         version = version_match.group(1)
11     else:
12         raise RuntimeError("Unable to find version string.")
13 
14 
15 with io.open('README.rst', encoding='utf8') as readme:
16     long_description = readme.read()
17 
18 
19 setup(
20     name='toga-core',
21     version=version,
22     description='A Python native, OS native GUI toolkit.',
23     long_description=long_description,
24     author='Russell Keith-Magee',
25     author_email='russell@keith-magee.com',
26     url='http://pybee.org/toga',
27     packages=find_packages(exclude='tests'),
28     python_requires='>=3.5',
29     package_data={
30         'toga': ['resources/*.icns', 'resources/*.png'],
31     },
32     include_package_data=True,
33     install_requires=[
34         'travertino>=0.1.0'
35     ],
36     tests_require=[
37         'toga-dummy==%s' % version
38     ],
39     license='New BSD',
40     classifiers=[
41         'Development Status :: 3 - Alpha',
42         'Intended Audience :: Developers',
43         'License :: OSI Approved :: BSD License',
44         'Operating System :: OS Independent',
45         'Programming Language :: Python :: 3',
46         'Programming Language :: Python :: 3.5',
47         'Programming Language :: Python :: 3.6',
48         'Programming Language :: Python :: 3.7',
49         'Programming Language :: Python :: 3 :: Only',
50         'Topic :: Software Development',
51         'Topic :: Software Development :: User Interfaces',
52         'Topic :: Software Development :: Widget Sets',
53     ],
54     test_suite='tests',
55     zip_safe=False,
56 )
57
```
--- 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/src/core/setup.py b/src/core/setup.py
--- a/src/core/setup.py
+++ b/src/core/setup.py
@@ -27,7 +27,7 @@
     packages=find_packages(exclude='tests'),
     python_requires='>=3.5',
     package_data={
-        'toga': ['resources/*.icns', 'resources/*.png'],
+        'toga': ['resources/*.icns', 'resources/*.ico', 'resources/*.png'],
     },
     include_package_data=True,
     install_requires=[

{"golden_diff": "diff --git a/src/core/setup.py b/src/core/setup.py\n--- a/src/core/setup.py\n+++ b/src/core/setup.py\n@@ -27,7 +27,7 @@\n     packages=find_packages(exclude='tests'),\n     python_requires='>=3.5',\n     package_data={\n-        'toga': ['resources/*.icns', 'resources/*.png'],\n+        'toga': ['resources/*.icns', 'resources/*.ico', 'resources/*.png'],\n     },\n     include_package_data=True,\n     install_requires=[\n", "issue": "Error looking for icon for tutorial for 0.3.0.dev9\nThis is with Python 3.6.5 in a clean venv:\r\n```\r\n(.venv) PS C:\\Users\\_\\Desktop\\toga_tutorial> python .\\helloworld.py\r\n[Winforms] No valid icon format available for C:\\Users\\brcan\\Desktop\\toga_tutorial\\.venv\\lib\\site-packages\\toga\\resources\\tiberius; fall back on Tiberius instead\r\n\r\nUnhandled Exception: Python.Runtime.PythonException: FileNotFoundException : Could not find file 'C:\\Users\\brcan\\Desktop\\toga_tutorial\\.venv\\lib\\site-packages\\toga\\resources\\tiberius.ico'.\r\n   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)\r\n   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)\r\n   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)\r\n   at System.Drawing.Icon..ctor(String fileName, Int32 width, Int32 height)\r\n   at Python.Runtime.Dispatcher.Dispatch(ArrayList args)\r\n   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)\r\n   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)\r\n   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n   at System.Threading.ThreadHelper.ThreadStart()\r\n```\n", "before_files": [{"content": "#/usr/bin/env python\nimport io\nimport re\n\nfrom setuptools import setup, find_packages\n\nwith io.open('toga/__init__.py', encoding='utf8') as version_file:\n    version_match = re.search(r\"^__version__ = ['\\\"]([^'\\\"]*)['\\\"]\", version_file.read(), re.M)\n    if version_match:\n        version = version_match.group(1)\n    else:\n        raise RuntimeError(\"Unable to find version string.\")\n\n\nwith io.open('README.rst', encoding='utf8') as readme:\n    long_description = readme.read()\n\n\nsetup(\n    name='toga-core',\n    version=version,\n    description='A Python native, OS native GUI toolkit.',\n    long_description=long_description,\n    author='Russell Keith-Magee',\n    author_email='russell@keith-magee.com',\n    url='http://pybee.org/toga',\n    packages=find_packages(exclude='tests'),\n    python_requires='>=3.5',\n    package_data={\n        'toga': ['resources/*.icns', 'resources/*.png'],\n    },\n    include_package_data=True,\n    install_requires=[\n        'travertino>=0.1.0'\n    ],\n    tests_require=[\n        'toga-dummy==%s' % version\n    ],\n    license='New BSD',\n    classifiers=[\n        'Development Status :: 3 - Alpha',\n        'Intended Audience :: Developers',\n        'License :: OSI Approved :: BSD License',\n        'Operating System :: OS Independent',\n        'Programming Language :: Python :: 3',\n        'Programming Language :: Python :: 3.5',\n        'Programming Language :: Python :: 3.6',\n        'Programming Language :: Python :: 3.7',\n        'Programming Language :: Python :: 3 :: Only',\n        'Topic :: Software Development',\n        'Topic :: Software Development :: User Interfaces',\n        'Topic :: Software Development :: Widget Sets',\n    ],\n    test_suite='tests',\n    zip_safe=False,\n)\n", "path": "src/core/setup.py"}], "after_files": [{"content": "#/usr/bin/env python\nimport io\nimport re\n\nfrom setuptools import setup, find_packages\n\nwith io.open('toga/__init__.py', encoding='utf8') as version_file:\n    version_match = re.search(r\"^__version__ = ['\\\"]([^'\\\"]*)['\\\"]\", version_file.read(), re.M)\n    if version_match:\n        version = version_match.group(1)\n    else:\n        raise RuntimeError(\"Unable to find version string.\")\n\n\nwith io.open('README.rst', encoding='utf8') as readme:\n    long_description = readme.read()\n\n\nsetup(\n    name='toga-core',\n    version=version,\n    description='A Python native, OS native GUI toolkit.',\n    long_description=long_description,\n    author='Russell Keith-Magee',\n    author_email='russell@keith-magee.com',\n    url='http://pybee.org/toga',\n    packages=find_packages(exclude='tests'),\n    python_requires='>=3.5',\n    package_data={\n        'toga': ['resources/*.icns', 'resources/*.ico', 'resources/*.png'],\n    },\n    include_package_data=True,\n    install_requires=[\n        'travertino>=0.1.0'\n    ],\n    tests_require=[\n        'toga-dummy==%s' % version\n    ],\n    license='New BSD',\n    classifiers=[\n        'Development Status :: 3 - Alpha',\n        'Intended Audience :: Developers',\n        'License :: OSI Approved :: BSD License',\n        'Operating System :: OS Independent',\n        'Programming Language :: Python :: 3',\n        'Programming Language :: Python :: 3.5',\n        'Programming Language :: Python :: 3.6',\n        'Programming Language :: Python :: 3.7',\n        'Programming Language :: Python :: 3 :: Only',\n        'Topic :: Software Development',\n        'Topic :: Software Development :: User Interfaces',\n        'Topic :: Software Development :: Widget Sets',\n    ],\n    test_suite='tests',\n    zip_safe=False,\n)\n", "path": "src/core/setup.py"}]}