robbyrussell/oh-my-zsh — pull request #2720 by Stealthii (2014-04-15 10:36:17+00:00)
Title: Add exclude-dir option only if grep supports it

Older versions of grep pre 2.5.2 did not have this option. Providing it
breaks grep use under oh-my-zsh on these systems. This patch adds a
check to ensure the option is only used if the manpages list it.