Allow Python 2.6, numpy 1.9 on osx to fail.
Allow Python 2.6, numpy 1.9 on osx to fail.

landlab/landlab,ManuSchmi88/landlab,csherwood-usgs/landlab,RondaStrauch/landlab,Carralex/landlab,cmshobe/landlab,SiccarPoint/landlab,amandersillinois/landlab,csherwood-usgs/landlab,laijingtao/landlab,RondaStrauch/landlab,SiccarPoint/landlab,Carralex/landlab,cmshobe/landlab,ManuSchmi88/landlab,laijingtao/landlab,cmshobe/landlab,landlab/landlab,RondaStrauch/landlab,ManuSchmi88/landlab,Carralex/landlab,amandersillinois/landlab,landlab/landlab