diff -r 43d08528223c Lib/test/test_urllib2.py
--- a/Lib/test/test_urllib2.py	Thu Jan 12 08:06:49 2012 +0100
+++ b/Lib/test/test_urllib2.py	Thu Jan 12 16:02:37 2012 +0100
@@ -10,7 +10,8 @@
 import urllib.request
 # The proxy bypass method imported below has logic specific to the OSX
 # proxy config data structure but is testable on all platforms.
-from urllib.request import Request, OpenerDirector, _proxy_bypass_macosx_sysconf
+from urllib.request import _proxy_bypass_macosx_sysconf
+from urllib.request import Request, OpenerDirector, quote
 import urllib.error
 
 # XXX
@@ -1425,6 +1426,11 @@
         self.assertEqual("http://www.python.org/~jeremy/",
                          self.get.get_full_url())
 
+        url_with_spaces = "http://www.python.org/url with/ a lot of spaces/"
+        req = Request(url_with_spaces)
+        self.assertEqual(quote(url_with_spaces, safe="%/:=&?~#+!$,;'@()*[]|"),
+                         req.get_full_url())
+
     def test_selector(self):
         self.assertEqual("/~jeremy/", self.get.get_selector())
         req = Request("http://www.python.org/")
diff -r 43d08528223c Lib/urllib/request.py
--- a/Lib/urllib/request.py	Thu Jan 12 08:06:49 2012 +0100
+++ b/Lib/urllib/request.py	Thu Jan 12 16:02:37 2012 +0100
@@ -195,7 +195,9 @@
                  origin_req_host=None, unverifiable=False,
                  method=None):
         # unwrap('<URL:type://host/path>') --> 'type://host/path'
-        self.full_url = unwrap(url)
+        # percent encode url, fixing lame server errors for e.g,
+        # like space within url paths.
+        self.full_url = quote(unwrap(url), safe="%/:=&?~#+!$,;'@()*[]|")
         self.full_url, self.fragment = splittag(self.full_url)
         self.data = data
         self.headers = {}