Unfortunately on a number of occasions, Skopeo has been released
officially with a `-dev` suffix in the version number. Assist in
catching this mistake at release time by the addition of a simple
conditional test. Note that it must be positively enabled by a
magic env. var. before executing the system tests.
Also (as suggested by @lsm5) update the TMT test to trigger the new
condition for future Fedora releases.
Signed-off-by: Chris Evich <cevich@redhat.com>
