A properly configured remote URI from our git repos will automatically
identify the remote repo to create the differential.
Reported by: des
Approved by: portmgr
Problem
When using git-svn or other non-pure-svn tooling the original subversion
URL is not present. This causes arcanist/phabricator to be unable to
determine which repository is being modified.
Solution
Restore callsign to .arcconfig to enable exact repository matching even
with git-svn.
Reported By: jhb