Fixes HOMEBREW_PRFIX when brew is outside $PATH
Fixes HOMEBREW_PRFIX when brew is outside $PATH

If brew is called with an explicit path, eg. './bin/brew',
HOMEBREW_PREFIX is set to an empty string resulting in failure of all
brew commands using HOMEBREW_PREFIX. This commit forces Pathname to
compile an absolute path, setting HOMEBREW_PREFIX correctly.

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