ansible: Correct git mirror update script initial clone

ansible: Correct git mirror update script initial clone

When '--mirror' isn't set, the remote references aren't always
pulled. To fix an existing repository that is just a bare clone, the
following commands can be run:

```
git remote rm origin
git remote add --mirror=fetch origin URL
git fetch --all
```

Change-Id: I9b713fe2dae523ba70a387adef23e87f98bb059a