If I merge from my target branch into a feature branch that is in a pull request (e.g. from master into feature/ISSUE-1), using "git merge --log", it includes the commit messages from all the new work on master in the merge commit.
Stash then shows all the issues from those commits being associated with the PR in the Stash UI.
In this case this is wrong - I have simply made my feature branch as up-to-date as possible and the PR has nothing to do with those issues.