Fix `shellenv` when using `-u`.
Fix `shellenv` when using `-u`.

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