Handle review URLs pointing directly at Gerrit

If a review URL is set to 'http://host/Gerrit' because the user
thinks that is the correct way to point repo at Gerrit, we should
be a bit more flexible and fix the URL by dropping the '/Gerrit'
suffix and replace it with '/ssh_info'.

Likewise, if a review URL points already at '/ssh_info' for a Gerrit
instance, we should leave it alone.

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/git_config.py b/git_config.py
index ed5a44a..971d146 100644
--- a/git_config.py
+++ b/git_config.py
@@ -273,9 +273,12 @@
       u = self.review
       if not u.startswith('http:') and not u.startswith('https:'):
         u = 'http://%s' % u
-      if not u.endswith('/'):
-        u += '/'
-      u += 'ssh_info'
+      if u.endswith('/Gerrit'):
+        u = u[:len(u) - len('/Gerrit')]
+      if not u.endswith('/ssh_info'):
+        if not u.endswith('/'):
+          u += '/'
+        u += 'ssh_info'
 
       try:
         info = urlopen(u).read()