Steps with problems marked with :
1. Create issue in JIRA with UTF8 characters (like ąćęłóśźż).
2. Click create branch from JIRA issue.
3. You've got broken branch name proposed by Stash.
4. Correct characters as originally written.
5. Fix the issue, push change, merge.
6. Error message displayed in commits list in stash, above branch selection:
"No branch or tag 'refs/heads/bugfix/ABC-123-branch-with-ąćęłóśźż' exists in repository 'repository-with-utf8-branches'".