Problem Definition

While it is currently possible in Bitbucket Server to globally define merge strategies for pull requests, this setting can be overridden on a per-repository basis. Depending on the strategy used during merge, information may be lost (by removing commits rather than creating a merge commit) that links commits to JIRA issues, pull requests, etc, which is critical information to maintain for audit purposes.

Suggested Solution

There should be a way for an administrator to define a non-overridable merge strategy to be applied to all repositories.

Workaround

Don't give anyone repository admin permissions. That way, only the project admin can modify these settings.