Fixed #8455: a lack of permissions in `MEDIA_ROOT` no longer causes an infinite loop when saving files. Thanks, carljm.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8639 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/files/storage.py

@@ -1,4 +1,5 @@
 import os
+import errno
 import urlparse
 
 from django.conf import settings
@@ -161,10 +162,13 @@ class FileSystemStorage(Storage):
                     finally:
                         locks.unlock(fd)
                         os.close(fd)
-            except OSError:
-                # Ooops, we need a new file name.
+            except OSError, e:
+                if e.errno == errno.EEXIST:
+                    # Ooops, the file exists. We need a new file name.
                     name = self.get_available_name(name)
                     full_path = self.path(name)
+                else:
+                    raise
             else:
                 # OK, the file save worked. Break out of the loop.
                 break