This reverts commit 2a25b63bb682c1546605bcbfb7ab9e828c4fe678.
Looking at other roles, we trigger building regardless of this.
It's better to always trigger it, because it's less fragile.
If the build fails and we only trigger it on "git changes"
then we won't trigger it for a while. That's not good.
Triggering it each and every time may seem like a waste,
but it supposedly runs quickly due to Docker caching.
653d1d7924