Do not delete the SQL dump too early
The change in baa15792 broke backup
restore fucnctionality. This would not lead to data loss, but it
prevented the restore script from working. This bug exists only in
7.14.0 release candidate versions, not in 7.13.
Reported in https://github.com/gitlabhq/gitlabhq/issues/9571 .
See merge request !1182
