For small single change pull requests have a full git merge in the history can be annoying since it clutter the history view (it uses up two lines, it may show connecting both branches existing at the same time even if there are no commits on master during that time).
We could try and instead find out if bitbucket can be made to allow fast forwards in the pull request merge (https://bitbucket.org/site/master/issue/6106/forced-non-fast-forward-merge-of-pull). Currently apparently bitbucket uses --no-ff ie it disallows fast forwards.
We could even think about forcing fast forwards only (https://bitbucket.org/site/master/issue/9589/force-fast-forward-only-merges-on-pull). This does however not work so well for big "feature" branches that are brought back into master and where a fast forward may fail and/or require extensive rebasing of the feature branch.