Cancel update if the current user doesn't have write permissions for the oh-my-zsh directory.
Merge pull request #2358 from n-st/master

Cancel update if the current user doesn't have write permissions for the oh-my-zsh directory.
Revert "Cancel update if the current user doesn't have write permissions for the oh-my-zsh directory."

This reverts commit 152e1e07e0397ecc3f1778ea597d081c33ee8ff4.
Upstream merge.