get-versions.sh: Fix detached head checkout failures

* get-versions.sh: Fix arbitrary branch checkout failures when
we're in detached state. If possible, use the original branch
name [which originates from a components definition file so it better
exist] before adjusting for release tag, as a first guess. That
should be better than checking out an arbitrary branch performance-wise.
Merge branch '2014.11' into jeremy-2014.11-tagging.

Conflicts (resolved):
	get-versions.sh

Fix executable status of tag-release.sh