Do not break built-in logging module when pip embedded in script
Do not break built-in logging module when pip embedded in script

Fixes #2553. When a Python script embeds pip and tries to log something from a different thread, an AttributeError is raised.
willingc/pip,rbtcollins/pip,fiber-space/pip,sigmavirus24/pip,benesch/pip,benesch/pip,wkeyword/pip,KarelJakubec/pip,techtonik/pip,pypa/pip,esc/pip,nthall/pip,KarelJakubec/pip,techtonik/pip,rouge8/pip,pypa/pip,luzfcb/pip,tdsmith/pip,harrisonfeng/pip,chaoallsome/pip,rouge8/pip,haridsv/pip,dstufft/pip,tdsmith/pip,zorosteven/pip,jmagnusson/pip,qbdsoft/pip,jasonkying/pip,xavfernandez/pip,RonnyPfannschmidt/pip,atdaemon/pip,KarelJakubec/pip,squidsoup/pip,nthall/pip,wkeyword/pip,zorosteven/pip,pfmoore/pip,Gabriel439/pip,erikrose/pip,ChristopherHogan/pip,zvezdan/pip,squidsoup/pip,h4ck3rm1k3/pip,fiber-space/pip,James-Firth/pip,chaoallsome/pip,RonnyPfannschmidt/pip,mindw/pip,esc/pip,sigmavirus24/pip,jmagnusson/pip,rbtcollins/pip,qbdsoft/pip,ChristopherHogan/pip,caosmo/pip,pradyunsg/pip,xavfernandez/pip,atdaemon/pip,harrisonfeng/pip,mujiansu/pip,Gabriel439/pip,zvezdan/pip,prasaianooz/pip,jythontools/pip,techtonik/pip,jasonkying/pip,sigmavirus24/pip,James-Firth/pip,alex/pip,mindw/pip,atdaemon/pip,wkeyword/pip,fiber-space/pip,zvezdan/pip,nthall/pip,mindw/pip,haridsv/pip,esc/pip,jythontools/pip,yati-sagade/pip,ChristopherHogan/pip,harrisonfeng/pip,RonnyPfannschmidt/pip,dstufft/pip,qbdsoft/pip,James-Firth/pip,tdsmith/pip,Gabriel439/pip,benesch/pip,ncoghlan/pip,rouge8/pip,pfmoore/pip,prasaianooz/pip,luzfcb/pip,rbtcollins/pip,alex/pip,yati-sagade/pip,erikrose/pip,sbidoul/pip,zenlambda/pip,jythontools/pip,jasonkying/pip,supriyantomaftuh/pip,zenlambda/pip,squidsoup/pip,chaoallsome/pip,ncoghlan/pip,erikrose/pip,jmagnusson/pip,prasaianooz/pip,xavfernandez/pip,zenlambda/pip,supriyantomaftuh/pip,caosmo/pip,natefoo/pip,h4ck3rm1k3/pip,luzfcb/pip,willingc/pip,pradyunsg/pip,zorosteven/pip,dstufft/pip,natefoo/pip,supriyantomaftuh/pip,willingc/pip,alex/pip,ncoghlan/pip,h4ck3rm1k3/pip,sbidoul/pip,caosmo/pip,natefoo/pip,mujiansu/pip,mujiansu/pip,haridsv/pip,yati-sagade/pip