Associate DVCS commits to JIRA issues by inserting the hash into JIRA

We are looking to configure Jira such that we can either have it maintain the associations or look up the associations. The "associations" are merely an n-to-n mapping of Jira Id and git hash. The associations could be modified through Jira or Stash. And, if possible, it would be convenient to still trigger associations by including the Jira Id in the commit message as we do now. In the latter case, the commit message would not itself represent the association - it merely initiates the association; one could subsequently remove this association without touching the commit message.

Due to the immutable history of git commits, I was surprised I was unable to find anyone else asking for this (save a few two-year-old requests for this for integration with svn).