rebase -i --update-refs can lead to deletion of branches

["herr.kaste" <herr.kaste@gmail.com>]

Hi,

I have the following:

While doing a

`$ git rebase --interactive  --update-refs X`

I *removed* the "update-ref" lines from the todo list.  The rebase runs
as expected and prints e.g.

```
Successfully rebased and updated refs/heads/test.
Updated the following refs with --update-refs:
refs/heads/master
refs/heads/permissive-interactive-rebase
refs/heads/variable-annotations-meta-block
```

After that all refs have been removed/deleted.

```
$ git branch  --list
* test
```

Now, I should just have not used `--update-refs` in the first place but anyway
I decide late that I rather don't want to update "master" etc. and it should
probably not delete the local refs.

Actually, I so love the new feature that I switched it *on* by default, and just
wanted to overwrite the behavior in the todo editor.

Regards
Caspar Duregger