Work around a urllib2 bug in Python < 2.4.2

When urllib2 base64-encodes the password needed for the Proxy-authorization
header, it forgets to remove the trailing "\n".  Later, a "\r\n" sequence
is appended to every header, as required by the standard.

Some proxies interpret the resulting "\n\r\n" sequence in the same way as
"\r\n\r\n": end of headers.  This usually doesn't cause trouble for this
request, but when the proxy tries to read the next one, it thinks the
request starts with some garbage and returns a "400 - Bad Request" error.

mercurial/httprepo.py

@@ -76,6 +76,14 b' def netlocunsplit(host, port, user=None,'
         return userpass + '@' + hostport
     return hostport
 
+# work around a bug in Python < 2.4.2
+# (it leaves a "\n" at the end of Proxy-authorization headers)
+class request(urllib2.Request):
+    def add_header(self, key, val):
+        if key.lower() == 'proxy-authorization':
+            val = val.strip()
+        return urllib2.Request.add_header(self, key, val)
+
 class httpsendfile(file):
     def __len__(self):
         return os.fstat(self.fileno()).st_size
@@ -239,7 +247,7 b' class httprepository(remoterepository):'
             if data:
                 self.ui.debug(_("sending %s bytes\n") %
                               headers.get('content-length', 'X'))
-            resp = urllib2.urlopen(urllib2.Request(cu, data, headers))
+            resp = urllib2.urlopen(request(cu, data, headers))
         except urllib2.HTTPError, inst:
             if inst.code == 401:
                 raise util.Abort(_('authorization failed'))