tab: fix Tab.for_formula versions (#687)
tab: fix Tab.for_formula versions (#687)

versions should be initialized even if formula is not installed
amar-laksh/brew_sudo,palxex/brew,claui/brew,Linuxbrew/brew,reelsense/brew,zmwangx/brew,reitermarkus/brew,konqui/brew,DomT4/brew,konqui/brew,gregory-nisbet/brew,Homebrew/brew,pseudocody/brew,konqui/brew,claui/brew,Homebrew/brew,muellermartin/dist,sjackman/homebrew,zmwangx/brew,reitermarkus/brew,Homebrew/brew,mgrimes/brew,MikeMcQuaid/brew,JCount/brew,reelsense/brew,hanxue/linuxbrew,JCount/brew,vitorgalvao/brew,mahori/brew,DomT4/brew,alyssais/brew,hanxue/linuxbrew,jmsundar/brew,tonyg/homebrew,konqui/brew,Linuxbrew/brew,mahori/brew,ilovezfs/brew,vitorgalvao/brew,nandub/brew,aw1621107/brew,reitermarkus/brew,ilovezfs/brew,amar-laksh/brew_sudo,bfontaine/brew,hanxue/linuxbrew,maxim-belkin/brew,mahori/brew,vitorgalvao/brew,pseudocody/brew,reelsense/brew,EricFromCanada/brew,sjackman/homebrew,jmsundar/brew,nandub/brew,pseudocody/brew,amar-laksh/brew_sudo,MikeMcQuaid/brew,MikeMcQuaid/brew,aw1621107/brew,Linuxbrew/brew,MikeMcQuaid/brew,DomT4/brew,JCount/brew,vitorgalvao/brew,reitermarkus/brew,EricFromCanada/brew,alyssais/brew,AnastasiaSulyagina/brew,ilovezfs/brew,aw1621107/brew,palxex/brew,mgrimes/brew,maxim-belkin/brew,EricFromCanada/brew,zmwangx/brew,jmsundar/brew,toonetown/homebrew,rwhogg/brew,JCount/brew,muellermartin/dist,nandub/brew,Homebrew/brew,palxex/brew,gregory-nisbet/brew,DomT4/brew,toonetown/homebrew,gregory-nisbet/brew,rwhogg/brew,sjackman/homebrew,Linuxbrew/brew,AnastasiaSulyagina/brew,rwhogg/brew,toonetown/homebrew,tonyg/homebrew,nandub/brew,tonyg/homebrew,bfontaine/brew,mgrimes/brew,AnastasiaSulyagina/brew,claui/brew,sjackman/homebrew,muellermartin/dist,maxim-belkin/brew,mahori/brew,bfontaine/brew,claui/brew,alyssais/brew,EricFromCanada/brew