install: fix --HEAD for formulae with head and devel but no stable
install: fix --HEAD for formulae with head and devel but no stable

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