Adapt search tests to new PyPI searches
Adapt search tests to new PyPI searches

- unmark test_multiple_search for failure
- search for nonexistentpackage instead of non-existent-package since PyPI
  seems to fallback to searches about "package" and manages to find
  things...

benesch/pip,ncoghlan/pip,James-Firth/pip,nthall/pip,willingc/pip,atdaemon/pip,rbtcollins/pip,sigmavirus24/pip,luzfcb/pip,xavfernandez/pip,zvezdan/pip,RonnyPfannschmidt/pip,esc/pip,James-Firth/pip,RonnyPfannschmidt/pip,alex/pip,ChristopherHogan/pip,alex/pip,mindw/pip,willingc/pip,ncoghlan/pip,techtonik/pip,natefoo/pip,zvezdan/pip,benesch/pip,ChristopherHogan/pip,fiber-space/pip,pradyunsg/pip,pypa/pip,fiber-space/pip,ChristopherHogan/pip,techtonik/pip,sigmavirus24/pip,pfmoore/pip,natefoo/pip,atdaemon/pip,sbidoul/pip,fiber-space/pip,rouge8/pip,jythontools/pip,rouge8/pip,pradyunsg/pip,dstufft/pip,luzfcb/pip,esc/pip,zvezdan/pip,nthall/pip,atdaemon/pip,esc/pip,jythontools/pip,benesch/pip,ncoghlan/pip,nthall/pip,James-Firth/pip,luzfcb/pip,rbtcollins/pip,rouge8/pip,mindw/pip,willingc/pip,xavfernandez/pip,techtonik/pip,sigmavirus24/pip,mindw/pip,pfmoore/pip,alex/pip,rbtcollins/pip,dstufft/pip,dstufft/pip,jythontools/pip,natefoo/pip,xavfernandez/pip,pypa/pip,RonnyPfannschmidt/pip,sbidoul/pip