From customer,

We have things set up at the moment where a push to a git repo tips of QuickBuild, and it builds each of the new commits present in the branch. Every once in a while, we discover a problem and chose to fixup the history by squashing in a fix, or rebasing the branch to the tip of master. Sometimes when we do this, QB fails the build because of some lookup that it's trying to do (I think to get the changes since the previous commit). Then we have to manually go back and tell it to build again.

It'd be nice not to have to do this. I'd rather QB just give up trying to discover the differences, and continue to build. Better, since we trigger for every commit, would be to just show the changes introduced in that commit, which should never fail.