Prevent deployment when new build on branch pending (#6397)
Prevent deployment when new build on branch pending (#6397)

When two commits followed closely on the same branch there was
a possibility that the earlier commit's associated build would run
slower than the later. This resulted in the deploy stage for the earlier
build running after the later.

This prevents the deploy stage from running on a build when another is
already in progress.
department-of-veterans-affairs/vets-website,department-of-veterans-affairs/vets-website