Hi,
Commit 59d3924fb (prompt: fix missing file errors in zsh) added the helper function eread() to git-prompt.sh. That function should be in the git "namespace", i.e. prefixed with __git_, otherwise it might collide with a function of the same name in the user's environment.
It's already in master and I don't have the means to send a patch fixing this ATM, sorry.
Best, Gábor