Amend repository extraction

Devstack changed the way it defines common github repositories. This
caused some repos being reported missing for our scripts. This change
amends the pattern used to recognise repositories from stackrc.

References:
    OS Change: I6161fa3194dbe8fbc25b6ee0e2fe3cc722a1cea4
    Github commit: cc52406a7843367c42e276b85cb9e73e4c525d51

Signed-off-by: Mate Lakat <mate.lakat@citrix.com>