Support usernames that contain '@' and ssh Git URLs

Our company-internal Gerrit uses federated logins (Shibboleth/SAML), and
the login names happen to include the at-signs. This needed a patch to
Gerrit ([1], released in 2.13.10) to allow them. Cloning using regular
git tools as well as through the gertty work, but `git-review --list`
complained because it couldn't parse these URLs.

[1] https://gerrit-review.googlesource.com/c/94914/

Change-Id: I6c1c75a585184ee3fb2847c1e6d30802e53f8b4c

git_review/cmd.py

@@ -525,7 +525,7 @@ def parse_gerrit_ssh_params_from_git_url(git_url):
             hostname = parsed_url.path[2:].split("/")[0]
 
         if "@" in hostname:
-            (username, hostname) = hostname.split("@")
+            (username, _, hostname) = hostname.rpartition("@")
         if ":" in hostname:
             (hostname, port) = hostname.split(":")