keg: cleanup aliases correctly.
keg: cleanup aliases correctly.

This was missed when I was focused on cleaning up versioned aliases.

Fixes #2992.

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