Don't do an inverted if test.

rest_framework/urlpatterns.py

@@ -6,28 +6,29 @@ from django.core.urlresolvers import RegexURLResolver
 def apply_suffix_patterns(urlpatterns, suffix_pattern, suffix_required):
     ret = []
     for urlpattern in urlpatterns:
-        if not isinstance(urlpattern, RegexURLResolver):
-            # Regular URL pattern
-
-            # Form our complementing '.format' urlpattern
-            regex = urlpattern.regex.pattern.rstrip('$') + suffix_pattern
-            view = urlpattern._callback or urlpattern._callback_str
-            kwargs = urlpattern.default_args
-            name = urlpattern.name
-            # Add in both the existing and the new urlpattern
-            if not suffix_required:
-                ret.append(urlpattern)
-            ret.append(url(regex, view, kwargs, name))
-        else:
+        if isinstance(urlpattern, RegexURLResolver):
             # Set of included URL patterns
             regex = urlpattern.regex.pattern
             namespace = urlpattern.namespace
             app_name = urlpattern.app_name
             kwargs = urlpattern.default_kwargs
+            # Add in the included patterns, after applying the suffixes
             patterns = apply_suffix_patterns(urlpattern.url_patterns,
                                              suffix_pattern,
                                              suffix_required)
             ret.append(url(regex, include(patterns, namespace, app_name), kwargs))
+
+        else:
+            # Regular URL pattern
+            regex = urlpattern.regex.pattern.rstrip('$') + suffix_pattern
+            view = urlpattern._callback or urlpattern._callback_str
+            kwargs = urlpattern.default_args
+            name = urlpattern.name
+            # Add in both the existing and the new urlpattern
+            if not suffix_required:
+                ret.append(urlpattern)
+            ret.append(url(regex, view, kwargs, name))
+
     return ret