Generalise the untap step so we can add to update
Generalise the untap step so we can add to update

brew-update needs to be able to unsymlink removed stuff from taps too.

Homebrew/brew,reelsense/brew,nandub/brew,MikeMcQuaid/brew,DomT4/brew,jmsundar/brew,AnastasiaSulyagina/brew,EricFromCanada/brew,mgrimes/brew,JCount/brew,hanxue/linuxbrew,gregory-nisbet/brew,mahori/brew,konqui/brew,konqui/brew,nandub/brew,mahori/brew,zmwangx/brew,claui/brew,nandub/brew,Linuxbrew/brew,staticfloat/brew,jmsundar/brew,MikeMcQuaid/brew,jmsundar/brew,mgrimes/brew,JCount/brew,vitorgalvao/brew,JCount/brew,DomT4/brew,maxim-belkin/brew,tonyg/homebrew,vitorgalvao/brew,sjackman/homebrew,reitermarkus/brew,konqui/brew,Linuxbrew/brew,aw1621107/brew,mahori/brew,gregory-nisbet/brew,pseudocody/brew,mistydemeo/homebrew,bfontaine/brew,rwhogg/brew,AnastasiaSulyagina/brew,reitermarkus/brew,MikeMcQuaid/brew,staticfloat/brew,MikeMcQuaid/brew,alyssais/brew,hanxue/linuxbrew,staticfloat/brew,aw1621107/brew,reelsense/brew,hanxue/linuxbrew,tonyg/homebrew,Linuxbrew/brew,Homebrew/brew,mahori/brew,reelsense/brew,ilovezfs/brew,amar-laksh/brew_sudo,alyssais/brew,sjackman/homebrew,muellermartin/dist,sjackman/homebrew,palxex/brew,Homebrew/brew,vitorgalvao/brew,toonetown/homebrew,EricFromCanada/brew,DomT4/brew,aw1621107/brew,rwhogg/brew,maxim-belkin/brew,ilovezfs/brew,palxex/brew,bfontaine/brew,EricFromCanada/brew,gordonmcshane/homebrew,ilovezfs/brew,toonetown/homebrew,DomT4/brew,claui/brew,zmwangx/brew,gregory-nisbet/brew,palxex/brew,mistydemeo/homebrew,gordonmcshane/homebrew,muellermartin/dist,nandub/brew,gordonmcshane/homebrew,claui/brew,Linuxbrew/brew,rwhogg/brew,amar-laksh/brew_sudo,mgrimes/brew,sjackman/homebrew,toonetown/homebrew,maxim-belkin/brew,muellermartin/dist,zmwangx/brew,bfontaine/brew,Homebrew/brew,AnastasiaSulyagina/brew,JCount/brew,tonyg/homebrew,alyssais/brew,pseudocody/brew,pseudocody/brew,reitermarkus/brew,claui/brew,vitorgalvao/brew,amar-laksh/brew_sudo,EricFromCanada/brew,reitermarkus/brew,mistydemeo/homebrew,konqui/brew