In Jira connected with Stash, you can create a feature branch for an issue using the button 'create branch'. (That is nice to track the commits in this issue.)
If a developer started working, but did not know that there is such an issue, they did not click the 'create branch'. Is there a way to assign an existing Git branch to an issue?
ex-Stash developer here.
Yes and no. Creating the branch though the UI is just a convenience. The important thing is that the name contains the JIRA key. If only one developer is working on the branch, it's fairly easy to just rename (delete + add) a branch with the appropriate name.
git checkout old-branch
git push -u origin old-branch:JIRAKEY-1234-something
git push origin :old-branch
Does that help?