* Before merging an item we set the remote ref to point to the current
branch HEAD.
* Instead of deleting the 'origin' remote in the executor we just set
it to a bogus value.
This feature enables jobs to perform quality checks on a per
commit basis (e.g. commit message checks).
For pull requests it was not possible before to determine which
commits are part of the current change.
Change-Id: I5de51917fbdfaa6ffee21dff7b63c520706c59eb
Simon Westphahl