"git svn dcommit" did not take into account the fact that a
svn+ssh:// URL with a username@ (typically used for pushing) refers
to the same SVN repository without the username@ and failed when
svn.pushmergeinfo option is set.
* jm/svn-pushmergeinfo-fix:
git-svn: fix svn.pushmergeinfo handling of svn+ssh usernames.