We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Gravatar default images do not load correctly


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `apps/authentication/templatetags/gravatar_url_resolver.py`
Content:
```
1 from django import template
2 from django.conf import settings
3 import urllib, hashlib
4  
5 register = template.Library()
6 
7 @register.assignment_tag(takes_context=True)
8 def gravatar_url(context, user, size):
9     default = "%s%s_%s.png" % (context['request'].META['HTTP_HOST'],
10                                settings.DEFAULT_PROFILE_PICTURE_PREFIX, user.gender)
11     gravatar_url = "https://www.gravatar.com/avatar/" + hashlib.md5(user.get_email().email).hexdigest() + "?"
12     gravatar_url += urllib.urlencode({'d': default, 's':str(size)})
13 
14     return gravatar_url
```
--- 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/apps/authentication/templatetags/gravatar_url_resolver.py b/apps/authentication/templatetags/gravatar_url_resolver.py
--- a/apps/authentication/templatetags/gravatar_url_resolver.py
+++ b/apps/authentication/templatetags/gravatar_url_resolver.py
@@ -6,8 +6,11 @@
 
 @register.assignment_tag(takes_context=True)
 def gravatar_url(context, user, size):
-    default = "%s%s_%s.png" % (context['request'].META['HTTP_HOST'],
+
+    prefix = "https://" if context['request'].is_secure() else "http://"
+    default = "%s%s%s_%s.png" % (prefix, context['request'].META['HTTP_HOST'],
                                settings.DEFAULT_PROFILE_PICTURE_PREFIX, user.gender)
+
     gravatar_url = "https://www.gravatar.com/avatar/" + hashlib.md5(user.get_email().email).hexdigest() + "?"
     gravatar_url += urllib.urlencode({'d': default, 's':str(size)})

{"golden_diff": "diff --git a/apps/authentication/templatetags/gravatar_url_resolver.py b/apps/authentication/templatetags/gravatar_url_resolver.py\n--- a/apps/authentication/templatetags/gravatar_url_resolver.py\n+++ b/apps/authentication/templatetags/gravatar_url_resolver.py\n@@ -6,8 +6,11 @@\n \n @register.assignment_tag(takes_context=True)\n def gravatar_url(context, user, size):\n-    default = \"%s%s_%s.png\" % (context['request'].META['HTTP_HOST'],\n+\n+    prefix = \"https://\" if context['request'].is_secure() else \"http://\"\n+    default = \"%s%s%s_%s.png\" % (prefix, context['request'].META['HTTP_HOST'],\n                                settings.DEFAULT_PROFILE_PICTURE_PREFIX, user.gender)\n+\n     gravatar_url = \"https://www.gravatar.com/avatar/\" + hashlib.md5(user.get_email().email).hexdigest() + \"?\"\n     gravatar_url += urllib.urlencode({'d': default, 's':str(size)})\n", "issue": "Gravatar default images do not load correctly\n\n", "before_files": [{"content": "from django import template\nfrom django.conf import settings\nimport urllib, hashlib\n \nregister = template.Library()\n\n@register.assignment_tag(takes_context=True)\ndef gravatar_url(context, user, size):\n    default = \"%s%s_%s.png\" % (context['request'].META['HTTP_HOST'],\n                               settings.DEFAULT_PROFILE_PICTURE_PREFIX, user.gender)\n    gravatar_url = \"https://www.gravatar.com/avatar/\" + hashlib.md5(user.get_email().email).hexdigest() + \"?\"\n    gravatar_url += urllib.urlencode({'d': default, 's':str(size)})\n\n    return gravatar_url", "path": "apps/authentication/templatetags/gravatar_url_resolver.py"}], "after_files": [{"content": "from django import template\nfrom django.conf import settings\nimport urllib, hashlib\n \nregister = template.Library()\n\n@register.assignment_tag(takes_context=True)\ndef gravatar_url(context, user, size):\n\n    prefix = \"https://\" if context['request'].is_secure() else \"http://\"\n    default = \"%s%s%s_%s.png\" % (prefix, context['request'].META['HTTP_HOST'],\n                               settings.DEFAULT_PROFILE_PICTURE_PREFIX, user.gender)\n\n    gravatar_url = \"https://www.gravatar.com/avatar/\" + hashlib.md5(user.get_email().email).hexdigest() + \"?\"\n    gravatar_url += urllib.urlencode({'d': default, 's':str(size)})\n\n    return gravatar_url", "path": "apps/authentication/templatetags/gravatar_url_resolver.py"}]}