TST: test for GH2623, object in frame upconverting a datetime64[ns] in another column
TST: test for GH2623, object in frame upconverting a datetime64[ns] in another column

MJuddBooth/pandas,zfrenchee/pandas,kdebrab/pandas,winklerand/pandas,pratapvardhan/pandas,linebp/pandas,nmartensen/pandas,Winand/pandas,dsm054/pandas,gfyoung/pandas,nmartensen/pandas,dsm054/pandas,gfyoung/pandas,Winand/pandas,rs2/pandas,DGrady/pandas,harisbal/pandas,winklerand/pandas,kdebrab/pandas,jmmease/pandas,pandas-dev/pandas,nmartensen/pandas,toobaz/pandas,harisbal/pandas,jreback/pandas,DGrady/pandas,GuessWhoSamFoo/pandas,jreback/pandas,nmartensen/pandas,amolkahat/pandas,harisbal/pandas,MJuddBooth/pandas,jorisvandenbossche/pandas,gfyoung/pandas,Winand/pandas,jmmease/pandas,harisbal/pandas,cython-testbed/pandas,dsm054/pandas,gfyoung/pandas,TomAugspurger/pandas,jorisvandenbossche/pandas,rs2/pandas,jreback/pandas,kdebrab/pandas,amolkahat/pandas,Winand/pandas,MJuddBooth/pandas,cbertinato/pandas,amolkahat/pandas,jmmease/pandas,jmmease/pandas,pratapvardhan/pandas,toobaz/pandas,linebp/pandas,jorisvandenbossche/pandas,jreback/pandas,pratapvardhan/pandas,datapythonista/pandas,nmartensen/pandas,datapythonista/pandas,cbertinato/pandas,MJuddBooth/pandas,GuessWhoSamFoo/pandas,winklerand/pandas,Winand/pandas,linebp/pandas,GuessWhoSamFoo/pandas,louispotok/pandas,TomAugspurger/pandas,jmmease/pandas,pandas-dev/pandas,TomAugspurger/pandas,pratapvardhan/pandas,pratapvardhan/pandas,louispotok/pandas,louispotok/pandas,linebp/pandas,DGrady/pandas,cython-testbed/pandas,Winand/pandas,winklerand/pandas,cython-testbed/pandas,MJuddBooth/pandas,zfrenchee/pandas,DGrady/pandas,rs2/pandas,DGrady/pandas,toobaz/pandas,toobaz/pandas,cython-testbed/pandas,jreback/pandas,nmartensen/pandas,louispotok/pandas,winklerand/pandas,datapythonista/pandas,dsm054/pandas,GuessWhoSamFoo/pandas,linebp/pandas,rs2/pandas,cbertinato/pandas,zfrenchee/pandas,dsm054/pandas,TomAugspurger/pandas,datapythonista/pandas,louispotok/pandas,toobaz/pandas,gfyoung/pandas,amolkahat/pandas,kdebrab/pandas,zfrenchee/pandas,DGrady/pandas,cbertinato/pandas,winklerand/pandas,pandas-dev/pandas,pandas-dev/pandas,amolkahat/pandas,kdebrab/pandas,jorisvandenbossche/pandas,linebp/pandas,jmmease/pandas,cython-testbed/pandas,zfrenchee/pandas,harisbal/pandas,cbertinato/pandas,GuessWhoSamFoo/pandas