Fix guessing content-type for already-downloaded file.
Fix guessing content-type for already-downloaded file.

ChristopherHogan/pip,erikrose/pip,blarghmatey/pip,Ivoz/pip,chaoallsome/pip,ChristopherHogan/pip,zorosteven/pip,sigmavirus24/pip,chaoallsome/pip,mattrobenolt/pip,Carreau/pip,esc/pip,fiber-space/pip,squidsoup/pip,habnabit/pip,RonnyPfannschmidt/pip,qbdsoft/pip,prasaianooz/pip,squidsoup/pip,rbtcollins/pip,mujiansu/pip,zvezdan/pip,benesch/pip,jmagnusson/pip,Gabriel439/pip,pfmoore/pip,jasonkying/pip,supriyantomaftuh/pip,wkeyword/pip,zorosteven/pip,fiber-space/pip,cjerdonek/pip,xavfernandez/pip,habnabit/pip,sigmavirus24/pip,yati-sagade/pip,harrisonfeng/pip,nthall/pip,mattrobenolt/pip,xavfernandez/pip,pypa/pip,mujiansu/pip,sbidoul/pip,harrisonfeng/pip,RonnyPfannschmidt/pip,davidovich/pip,supriyantomaftuh/pip,zenlambda/pip,graingert/pip,ncoghlan/pip,squidsoup/pip,alex/pip,ianw/pip,tdsmith/pip,msabramo/pip,zenlambda/pip,dstufft/pip,pypa/pip,harrisonfeng/pip,qbdsoft/pip,graingert/pip,alquerci/pip,atdaemon/pip,haridsv/pip,xavfernandez/pip,atdaemon/pip,tdsmith/pip,mindw/pip,willingc/pip,Carreau/pip,pradyunsg/pip,minrk/pip,prasaianooz/pip,techtonik/pip,davidovich/pip,pjdelport/pip,patricklaw/pip,habnabit/pip,pradyunsg/pip,benesch/pip,alex/pip,jythontools/pip,qwcode/pip,jythontools/pip,zvezdan/pip,msabramo/pip,davidovich/pip,Ivoz/pip,Gabriel439/pip,haridsv/pip,natefoo/pip,h4ck3rm1k3/pip,wkeyword/pip,sigmavirus24/pip,natefoo/pip,yati-sagade/pip,ianw/pip,rouge8/pip,patricklaw/pip,natefoo/pip,alex/pip,jamezpolley/pip,willingc/pip,luzfcb/pip,benesch/pip,graingert/pip,ncoghlan/pip,chaoallsome/pip,luzfcb/pip,jasonkying/pip,atdaemon/pip,zorosteven/pip,mindw/pip,KarelJakubec/pip,techtonik/pip,esc/pip,caosmo/pip,Gabriel439/pip,caosmo/pip,yati-sagade/pip,rouge8/pip,pjdelport/pip,cjerdonek/pip,rbtcollins/pip,minrk/pip,blarghmatey/pip,erikrose/pip,alquerci/pip,jmagnusson/pip,h4ck3rm1k3/pip,jamezpolley/pip,zvezdan/pip,jythontools/pip,jmagnusson/pip,h4ck3rm1k3/pip,James-Firth/pip,supriyantomaftuh/pip,luzfcb/pip,ChristopherHogan/pip,dstufft/pip,jamezpolley/pip,rouge8/pip,RonnyPfannschmidt/pip,sbidoul/pip,dstufft/pip,pjdelport/pip,jasonkying/pip,mindw/pip,tdsmith/pip,zenlambda/pip,erikrose/pip,pfmoore/pip,rbtcollins/pip,haridsv/pip,KarelJakubec/pip,ncoghlan/pip,James-Firth/pip,KarelJakubec/pip,wkeyword/pip,mujiansu/pip,willingc/pip,blarghmatey/pip,James-Firth/pip,qbdsoft/pip,qwcode/pip,nthall/pip,prasaianooz/pip,techtonik/pip,nthall/pip,esc/pip,fiber-space/pip,caosmo/pip