TST: Fix ImportError in runtests.py (fixes #5273)
TST: Fix ImportError in runtests.py (fixes #5273)

In numpy/testing/__init__.py, import Tester before importing numpy core

larsmans/numpy,nguyentu1602/numpy,nbeaver/numpy,WillieMaddox/numpy,skymanaditya1/numpy,rmcgibbo/numpy,Yusa95/numpy,bertrand-l/numpy,MaPePeR/numpy,leifdenby/numpy,yiakwy/numpy,sonnyhu/numpy,mwiebe/numpy,kirillzhuravlev/numpy,stuarteberg/numpy,jorisvandenbossche/numpy,larsmans/numpy,abalkin/numpy,ChristopherHogan/numpy,Yusa95/numpy,MSeifert04/numpy,mindw/numpy,pyparallel/numpy,leifdenby/numpy,githubmlai/numpy,ddasilva/numpy,cjermain/numpy,WillieMaddox/numpy,hainm/numpy,cowlicks/numpy,ChristopherHogan/numpy,madphysicist/numpy,ChanderG/numpy,skwbc/numpy,dwillmer/numpy,CMartelLML/numpy,argriffing/numpy,hainm/numpy,bringingheavendown/numpy,mathdd/numpy,brandon-rhodes/numpy,KaelChen/numpy,mindw/numpy,has2k1/numpy,anntzer/numpy,MaPePeR/numpy,pbrod/numpy,anntzer/numpy,ahaldane/numpy,sigma-random/numpy,njase/numpy,ChristopherHogan/numpy,SiccarPoint/numpy,skwbc/numpy,mhvk/numpy,sigma-random/numpy,moreati/numpy,tdsmith/numpy,grlee77/numpy,pizzathief/numpy,ajdawson/numpy,cjermain/numpy,endolith/numpy,KaelChen/numpy,naritta/numpy,musically-ut/numpy,jonathanunderwood/numpy,naritta/numpy,yiakwy/numpy,dch312/numpy,tacaswell/numpy,ViralLeadership/numpy,pbrod/numpy,pdebuyl/numpy,GrimDerp/numpy,ChanderG/numpy,grlee77/numpy,numpy/numpy,jonathanunderwood/numpy,ESSS/numpy,madphysicist/numpy,gfyoung/numpy,GaZ3ll3/numpy,ajdawson/numpy,joferkington/numpy,b-carter/numpy,chiffa/numpy,larsmans/numpy,ssanderson/numpy,AustereCuriosity/numpy,Srisai85/numpy,sonnyhu/numpy,bmorris3/numpy,ContinuumIO/numpy,ahaldane/numpy,SunghanKim/numpy,tdsmith/numpy,MSeifert04/numpy,endolith/numpy,tynn/numpy,ahaldane/numpy,nbeaver/numpy,Eric89GXL/numpy,ESSS/numpy,dato-code/numpy,mhvk/numpy,rgommers/numpy,grlee77/numpy,musically-ut/numpy,bmorris3/numpy,gmcastil/numpy,Srisai85/numpy,jakirkham/numpy,ChristopherHogan/numpy,dwillmer/numpy,AustereCuriosity/numpy,kiwifb/numpy,rajathkumarmp/numpy,brandon-rhodes/numpy,Yusa95/numpy,dimasad/numpy,MichaelAquilina/numpy,mwiebe/numpy,cjermain/numpy,charris/numpy,Dapid/numpy,jschueller/numpy,argriffing/numpy,chiffa/numpy,SiccarPoint/numpy,Eric89GXL/numpy,mortada/numpy,pdebuyl/numpy,Anwesh43/numpy,mingwpy/numpy,ahaldane/numpy,behzadnouri/numpy,jorisvandenbossche/numpy,GrimDerp/numpy,ekalosak/numpy,hainm/numpy,joferkington/numpy,Linkid/numpy,Srisai85/numpy,mhvk/numpy,b-carter/numpy,ahaldane/numpy,BabeNovelty/numpy,cowlicks/numpy,stuarteberg/numpy,madphysicist/numpy,gfyoung/numpy,ViralLeadership/numpy,pizzathief/numpy,b-carter/numpy,dimasad/numpy,utke1/numpy,groutr/numpy,jorisvandenbossche/numpy,nguyentu1602/numpy,jorisvandenbossche/numpy,empeeu/numpy,empeeu/numpy,GaZ3ll3/numpy,mattip/numpy,ekalosak/numpy,musically-ut/numpy,ekalosak/numpy,mingwpy/numpy,rherault-insa/numpy,GaZ3ll3/numpy,groutr/numpy,mindw/numpy,mhvk/numpy,sonnyhu/numpy,numpy/numpy,yiakwy/numpy,ddasilva/numpy,grlee77/numpy,mathdd/numpy,simongibbons/numpy,jschueller/numpy,pyparallel/numpy,rajathkumarmp/numpy,dimasad/numpy,solarjoe/numpy,Anwesh43/numpy,CMartelLML/numpy,rajathkumarmp/numpy,kirillzhuravlev/numpy,ChanderG/numpy,joferkington/numpy,has2k1/numpy,brandon-rhodes/numpy,stuarteberg/numpy,jorisvandenbossche/numpy,skymanaditya1/numpy,drasmuss/numpy,SunghanKim/numpy,bmorris3/numpy,pizzathief/numpy,tdsmith/numpy,dch312/numpy,pizzathief/numpy,sigma-random/numpy,endolith/numpy,dwillmer/numpy,pbrod/numpy,jankoslavic/numpy,rhythmsosad/numpy,numpy/numpy,has2k1/numpy,rherault-insa/numpy,drasmuss/numpy,CMartelLML/numpy,gmcastil/numpy,nguyentu1602/numpy,gmcastil/numpy,trankmichael/numpy,SunghanKim/numpy,Eric89GXL/numpy,empeeu/numpy,shoyer/numpy,chatcannon/numpy,felipebetancur/numpy,pbrod/numpy,AustereCuriosity/numpy,seberg/numpy,ChanderG/numpy,BabeNovelty/numpy,argriffing/numpy,abalkin/numpy,SiccarPoint/numpy,cowlicks/numpy,skymanaditya1/numpy,dch312/numpy,WarrenWeckesser/numpy,kiwifb/numpy,kiwifb/numpy,skymanaditya1/numpy,joferkington/numpy,GrimDerp/numpy,BMJHayward/numpy,empeeu/numpy,Linkid/numpy,cjermain/numpy,dato-code/numpy,maniteja123/numpy,rgommers/numpy,madphysicist/numpy,sigma-random/numpy,dato-code/numpy,felipebetancur/numpy,Eric89GXL/numpy,bertrand-l/numpy,mortada/numpy,simongibbons/numpy,MichaelAquilina/numpy,jankoslavic/numpy,charris/numpy,maniteja123/numpy,Anwesh43/numpy,ajdawson/numpy,bringingheavendown/numpy,WarrenWeckesser/numpy,behzadnouri/numpy,KaelChen/numpy,mattip/numpy,Srisai85/numpy,MSeifert04/numpy,rudimeier/numpy,bmorris3/numpy,shoyer/numpy,has2k1/numpy,ssanderson/numpy,ekalosak/numpy,ContinuumIO/numpy,drasmuss/numpy,mattip/numpy,KaelChen/numpy,mhvk/numpy,jankoslavic/numpy,WillieMaddox/numpy,githubmlai/numpy,BMJHayward/numpy,WarrenWeckesser/numpy,dimasad/numpy,utke1/numpy,rhythmsosad/numpy,felipebetancur/numpy,shoyer/numpy,nbeaver/numpy,kirillzhuravlev/numpy,shoyer/numpy,charris/numpy,tacaswell/numpy,sinhrks/numpy,CMartelLML/numpy,simongibbons/numpy,mortada/numpy,rudimeier/numpy,solarjoe/numpy,ViralLeadership/numpy,naritta/numpy,pdebuyl/numpy,gfyoung/numpy,anntzer/numpy,mathdd/numpy,groutr/numpy,simongibbons/numpy,sinhrks/numpy,BMJHayward/num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