Fix diagnostic when only keep_file is in sbin.
Fix diagnostic when only keep_file is in sbin.

Brew creates the keep_file itself and then complains about files in sbin.

mahori/brew,EricFromCanada/brew,JCount/brew,reitermarkus/brew,claui/brew,Homebrew/brew,vitorgalvao/brew,reitermarkus/brew,Homebrew/brew,konqui/brew,konqui/brew,MikeMcQuaid/brew,nandub/brew,konqui/brew,Homebrew/brew,sjackman/homebrew,JCount/brew,mahori/brew,MikeMcQuaid/brew,sjackman/homebrew,EricFromCanada/brew,MikeMcQuaid/brew,vitorgalvao/brew,vitorgalvao/brew,JCount/brew,Homebrew/brew,mahori/brew,mahori/brew,sjackman/homebrew,reitermarkus/brew,claui/brew,JCount/brew,EricFromCanada/brew,claui/brew,reitermarkus/brew,claui/brew,sjackman/homebrew,vitorgalvao/brew,MikeMcQuaid/brew,nandub/brew,nandub/brew,nandub/brew,EricFromCanada/brew,konqui/brew