Custom default commit messages
A small new feature: you can now return a default merge (or squash) commit message from your custom review completion condition, using any and all review state data at your disposal. These messages will be used instead of the built-in ones when merging from within Reviewable, and can be edited / overwritten by the user as normal.
Look for defaultMergeCommitMessage and defaultSquashCommitMessage in the docs for details.