Tweak backup-everything script just a bit more

check git status of rattail src prior to upgrading that, etc.

rattail_fabric/backup.py

@@ -76,6 +76,7 @@ def deploy_backup_app(deploy, envname, mkvirtualenv=True, user='rattail',
             sudo('git clone https://rattailproject.org/git/rattail.git src/rattail', user=user)
         with cd('src/rattail'):
             sudo('git pull', user=user)
+            deploy_generic('backup/git-exclude', '.git/info/exclude', owner=user)
         sudo('bin/pip install --upgrade --upgrade-strategy eager --editable src/rattail', user=user)
 
         # TODO: this should not be necessary