fix: release_collection should use code matching tag

[richm]

release_collection was not ensuring that the code checked out to
use to build the collection matched the tag/hash specified.

The code will now ensure:

• if --no-update was used, just ensure the given cur_ref is
  checked out, or main HEAD if cur_ref is None
• if cur_ref was set to a tag or commit hash, and there have been
  no updates to the role code since that tag/hash, the tag/hash will
  be checked out
• if there have been updates to the role code since the cur_ref
  • if there is a new tag, check out that tag
  • elif use_commit_hash is set, use main HEAD which is already checked
    out
  • else there have been role updates, but not yet tagged, and we
    are not using the commit hash - ensure cur_ref is checked out

Signed-off-by: Rich Megginson rmeggins@redhat.com

[richm]

I want to get this merged before the next nightly build. I've tested it locally and it works.