Fixed #16812 -- Percent-encode URLs in verify_exists, to fix test failures on Python 2.5 and 2.6.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16838 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/validators.py

 import platform
 import re
+import urllib
 import urllib2
 import urlparse
 
@@ -92,6 +93,8 @@ class URLValidator(RegexValidator):
                 "User-Agent": self.user_agent,
             }
             url = url.encode('utf-8')
+            # Quote characters from the unreserved set, refs #16812
+            url = urllib.quote(url, "!*'();:@&=+$,/?#[]")
             broken_error = ValidationError(
                 _(u'This URL appears to be a broken link.'), code='invalid_link')
             try: