integration tests: allow env overriding
integration tests: allow env overriding

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