Fixed #18210 -- Escaped special characters in reverse prefixes.

Ensured that special characters passed in to reverse via the
prefix argument are properly escaped so that calls to
django.utils.regex_helpers.normalize and/or string formatting
operations don't result in exceptions.

Thanks to toofishes for the error report.

django/core/urlresolvers.py

@@ -16,6 +16,7 @@ from django.core.exceptions import ImproperlyConfigured, ViewDoesNotExist
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_str, force_text, iri_to_uri
 from django.utils.functional import memoize, lazy
+from django.utils.http import urlquote
 from django.utils.importlib import import_module
 from django.utils.module_loading import module_has_submodule
 from django.utils.regex_helper import normalize
@@ -379,7 +380,8 @@ class RegexURLResolver(LocaleRegexProvider):
         except (ImportError, AttributeError) as e:
             raise NoReverseMatch("Error importing '%s': %s." % (lookup_view, e))
         possibilities = self.reverse_dict.getlist(lookup_view)
-        prefix_norm, prefix_args = normalize(_prefix)[0]
+
+        prefix_norm, prefix_args = normalize(urlquote(_prefix))[0]
         for possibility, pattern, defaults in possibilities:
             for result, params in possibility:
                 if args:
@@ -398,8 +400,8 @@ class RegexURLResolver(LocaleRegexProvider):
                     if not matches:
                         continue
                     unicode_kwargs = dict([(k, force_text(v)) for (k, v) in kwargs.items()])
-                    candidate = (prefix_norm + result) % unicode_kwargs
-                if re.search('^%s%s' % (_prefix, pattern), candidate, re.UNICODE):
+                    candidate = (prefix_norm.replace('%', '%%') + result) % unicode_kwargs
+                if re.search('^%s%s' % (prefix_norm, pattern), candidate, re.UNICODE):
                     return candidate
         # lookup_view can be URL label, or dotted path, or callable, Any of
         # these can be passed in at the top, but callables are not friendly in

tests/regressiontests/urlpatterns_reverse/tests.py

@@ -171,6 +171,18 @@ class URLPatternReverse(TestCase):
         # Reversing None should raise an error, not return the last un-named view.
         self.assertRaises(NoReverseMatch, reverse, None)
 
+    def test_prefix_braces(self):
+        self.assertEqual('/%7B%7Binvalid%7D%7D/includes/non_path_include/',
+               reverse('non_path_include', prefix='/{{invalid}}/'))
+
+    def test_prefix_parenthesis(self):
+        self.assertEqual('/bogus%29/includes/non_path_include/',
+               reverse('non_path_include', prefix='/bogus)/'))
+
+    def test_prefix_format_char(self):
+        self.assertEqual('/bump%2520map/includes/non_path_include/',
+               reverse('non_path_include', prefix='/bump%20map/'))
+
 class ResolverTests(unittest.TestCase):
     def test_resolver_repr(self):
         """