olivierverdier/zsh-git-prompt — pull request #34 by Kynde (2013-11-19 19:40:44+00:00)
Title: special characters would seem to need one char glitches %1G (or just %G)

My tab completion gets all wonky unless the special chars are glitched to have length 1 using %1G (or just %G).
I'm no expert in this, but this fixed it for me. Fedora 19, zsh 5.0.2.