Replace `Set::difference` with `Set::^`.
Replace `Set::difference` with `Set::^`.

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