readall: check for shadowed aliases.
readall: check for shadowed aliases.

If an alias has the same name as a formula then weirdness will result
so ensure this causes `readall` to fail.

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