Fix typo in lib/heat

With the change https://review.openstack.org/43006 a typo was
introduced. This change fixes it.

Change-Id: Iebcbfe49d779552c17f6ab216976149f332b772c
change git show to | head -1

git show uses default system pager, which for people that have
funky pagers, goes sideways. Pipe this through head -1 to ensure
we only get the single change line we care about.

Change-Id: Iff22612b555bf58fe12101701cfe593f37e8f8de
Merge "change git show to | head -1"
Merge "Fix typo in lib/heat"
Merge branch 'master' of github.com:openstack-dev/devstack