Jira: 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?