* Fix UnboundLocalError remote_head in git
Fixes#5505
The use of remote_head was a leftover of #4562.
remote_head is not necessary, since the repo is unchanged anyway and
after is set correctly.
Further changes:
* Set changed=True and msg once local_mods are detected and reset.
* Remove need_fetch that is always True (due to previous if) to improve
clarity
* Don't exit early for local_mods but run submodules update and
switch_version
* Add test for git with local modifications
afca957396