BUG: Fixed mask_rowcols().
BUG: Fixed mask_rowcols().

Previous implementation relied on ma.asarray() to always create
a new object.

See gh-4043.

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