robbyrussell/oh-my-zsh — pull request #2383 by Nitrodist (2013-12-30 08:15:42+00:00)
Title: Fix itchy theme rvm-prompt invocation by silencing error messages

If rvm-prompt or rbenv isn't found within the system, then the
following error message is displayed:

zsh: command not found: rvm-prompt

Silencing standard error while invoking these commands fixes this
problem.