Fix fish_prompt function.
Fix fish_prompt function.

plague-doctor/bash-git-prompt,plague-doctor/bash-git-prompt,plague-doctor/bash-git-prompt,ogr3/bash-git-prompt,gullevek/bash-git-prompt,gullevek/bash-git-prompt,ogr3/bash-git-prompt,magicmonty/bash-git-prompt,magicmonty/bash-git-prompt,gullevek/bash-git-prompt,ogr3/bash-git-prompt,magicmonty/bash-git-prompt