Collapse/expand side bar shortcut not working on Mac in some keyboard layouts

In repository issues view, all keyboard shortcuts are working as expected, except

"[" - Collapse/expand side bar

On the same machine with the same browser and same keyboard setup this shortcut is working fine in Atlassian's JIRA on demand.

MAC mini, 64bit, Mavericks 10.9.3.
Safari 7.0.4, German keyboard. ("[" is option-5).

Workaround: change the keyboard to an English variant and press "ü". This workaround is not satisfactory, as changing the keyboard layout just for this shortcut to work is not practical.