Add missing rmtree import in test_uninstall.
Add missing rmtree import in test_uninstall.

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