Looks like phabricator has changed how they store usernames on clone urls.

This is basically cargo-cult; I'll be looking at the cron logs to make
sure we don't try to add new repos after this.

Auditors: alpert

Test Plan:
Ran
   ./update_phabricator_repositories.py -n /tmp
and saw it say:
   Adding 0 new repositories to phabricator
   Removing 0 deleted repositories from phabricator