handle more varied top_level.txt files in distributions
handle more varied top_level.txt files in distributions

Deal with distributions that do not have the top_level.txt metadata
file, or that have more than one module name listed in it.

Change-Id: I7d21f4ba674ee95d072b0bc8e5f22b5b4b7a32b4
Closes-Bug: #1719465
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/cliff,dtroyer/cliff,dtroyer/cliff,openstack/cliff