Right now the default homu flow when using travis causes these builds:

1. Original PR commit built by travis (which is actually a merge commit with master)
2. auto branch when homu merges for testing
3. master branch when the final merge happens

Build 3 is redundant always, since that merge is always a fast forward with homu. You can remove this spurious build by adding branches: except: - master to .travis.yml, but unfortunately that turns of PR builds altogether.

However, Build 2 is often redundant as well. Travis CI already tests a merge commit, not the branch commit. In the case where master has not advanced past where homu tested it, homu could skip this build altogether and merge immediately. This would make the workflow even faster.