When “Squash & Merge” a branch in a PR, the default commit message is either:
the commit message of the the commit in the PR, if the PR has a single commit;
the title of the PR’s and the description from all commits’ titles, if the PR has more than one commits.
As this behavior is inconsistent, it often result in inconsistent merge messages. Is there a way to configure the default commit message for “Squash & Merge”?