Fixed #26039 -- Unwrapped nested partials in URL reversal.

Prior to Python 3.5 nested partials need to be fully "unfolded"
to get the actual function.

1 files changed, 3 insertions, 1 deletions

diff --git a/django/urls/resolvers.py b/django/urls/resolvers.py
index 7b9db5506f..0208601f79 100644
--- a/django/urls/resolvers.py
+++ b/django/urls/resolvers.py
@@ -135,7 +135,9 @@ class RegexURLPattern(LocaleRegexProvider):
         'path.to.ClassBasedView').
         """
         callback = self.callback
-        if isinstance(callback, functools.partial):
+        # Python 3.5 collapses nested partials, so can change "while" to "if"
+        # when it's the minimum supported version.
+        while isinstance(callback, functools.partial):
             callback = callback.func
         if not hasattr(callback, '__name__'):
             return callback.__module__ + "." + callback.__class__.__name__