Hotfix for filtered_args breaking brew upgrade
Hotfix for filtered_args breaking brew upgrade

The `filtered_args` method added to the `FormulaInstaller` makes a call
`ARGV.formulae`. Unfortunately, `ARGV.formulae` will throw a
`FormulaUnspecifiedError` instead of returning an empty list. This patch
avoids the issue by checking `ARGV.named.empty?` before calling
`ARGV.formulae`.

Fixes Homebrew/homebrew#8576.

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