sorin-ionescu/prezto — pull request #750 by xals (2014-12-05 11:02:28+00:00)
Title: Reuse existing alias for grep.

With GREP_OPTIONS beeing removed, I updated my local copy of oh-my-zsh using an alias. But using prezto after oh-my-zsh overrides the grep alias.

I think this is a good solution to keep the previous alias.