Add datetime functions (which should all fail).
Add datetime functions (which should all fail).

astropy/astropy,astropy/astropy,dhomeier/astropy,lpsinger/astropy,larrybradley/astropy,MSeifert04/astropy,saimn/astropy,stargaser/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,aleksandr-bakanov/astropy,stargaser/astropy,MSeifert04/astropy,StuartLittlefair/astropy,astropy/astropy,bsipocz/astropy,StuartLittlefair/astropy,lpsinger/astropy,dhomeier/astropy,dhomeier/astropy,stargaser/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,mhvk/astropy,mhvk/astropy,StuartLittlefair/astropy,bsipocz/astropy,aleksandr-bakanov/astropy,MSeifert04/astropy,larrybradley/astropy,saimn/astropy,pllim/astropy,larrybradley/astropy,astropy/astropy,MSeifert04/astropy,saimn/astropy,astropy/astropy,lpsinger/astropy,dhomeier/astropy,stargaser/astropy,mhvk/astropy,mhvk/astropy,pllim/astropy,pllim/astropy,lpsinger/astropy,StuartLittlefair/astropy,pllim/astropy,bsipocz/astropy,pllim/astropy,larrybradley/astropy,StuartLittlefair/astropy,saimn/astropy,saimn/astropy,mhvk/astropy,larrybradley/astropy,bsipocz/astropy