Build wheels against constraints

I was looking at wheel build failures, and in some cases builds fail
because they're not constrained to versions already in the
constraints.

For example; pylxd failed to build a wheel [1] due to [2], but
upper-constraints.txt would have kept urllib to 1.22.  Similarly
several django plugins fail on python2 as they try to bring in Django2
which only works with python3.

Pass the upper-constraints.txt to the wheel build to ensure consistent
building.

[1] http://logs.openstack.org/periodic/git.openstack.org/openstack/requirements/master/publish-wheel-mirror-centos-7/723e75b/python2/failed.txt

[2] https://github.com/requests/requests/issues/4673

Change-Id: I788994b69afd2769489454a3b16f84bea4c56e59

roles/build-wheels/files/wheel-build.sh

@@ -40,7 +40,9 @@ for BRANCH in master $BRANCHES; do
     cat /tmp/upper-constraints.txt | \
         parallel --files --progress --joblog ${LOGS}/$SHORT_BRANCH-job.log \
                 --results ${LOGS}/build/$SHORT_BRANCH \
-                build_env/bin/pip --verbose wheel -w $WHEELHOUSE_DIR {}
+                build_env/bin/pip --verbose wheel \
+                -c /tmp/upper-constraints.txt \
+                -w $WHEELHOUSE_DIR {}
     set -e
 
     # Column $7 is the exit status of the job, $14 is the last