core: fix the detection of the release
core: fix the detection of the release

Follow the rule:
- X.0 -> return X
  This matches the pre-existing behavior and it provides
  the existing consumers what they expect.
- X.Y, Y!=0 -> return X.Y
  This is the new case, currently not handled.

Change-Id: I99ce8a1652f26cb422678e299f1761ea9d2e6e78

redhat-openstack/octario,redhat-openstack/octario