Cannot choose branch when creating issue

[kernie]

• Gitea version (or commit ref): 1.13.1
• Git version: 2.17.1
• Operating system: Ubuntu Server 18.04
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL): Simply create issue and specify branch
  • No
• Log gist:

Description

When creating a new issue, I want to specify the branch. So I choose from the menu on the right. After clicking only site reloads, but nothing (visible) happens, branch is not marked nor stored as selected.

Screenshots