Fix :gzip_only extraction
Fix :gzip_only extraction

gunzip can only extract files in-place, so just shelling out to
gunzip was actually leaving the uncompressed file in Homebrew's cache,
not in the temporary directory. (It also destroyed the original
compressed file.)

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