formula_installer: minor refactoring
formula_installer: minor refactoring

claui/brew,EricFromCanada/brew,claui/brew,nandub/brew,nandub/brew,JCount/brew,Homebrew/brew,MikeMcQuaid/brew,claui/brew,MikeMcQuaid/brew,MikeMcQuaid/brew,Homebrew/brew,claui/brew,EricFromCanada/brew,JCount/brew,nandub/brew,MikeMcQuaid/brew,JCount/brew,Homebrew/brew,EricFromCanada/brew,Homebrew/brew,EricFromCanada/brew,JCount/brew,nandub/brew