Fix .travis.yml error
Fix .travis.yml error

bzero/networkx,farhaanbukhsh/networkx,jakevdp/networkx,cmtm/networkx,Sixshaman/networkx,blublud/networkx,harlowja/networkx,NvanAdrichem/networkx,wasade/networkx,harlowja/networkx,michaelpacer/networkx,ghdk/networkx,dmoliveira/networkx,farhaanbukhsh/networkx,jni/networkx,goulu/networkx,jni/networkx,ltiao/networkx,dhimmel/networkx,blublud/networkx,ionanrozenfeld/networkx,dmoliveira/networkx,sharifulgeo/networkx,ionanrozenfeld/networkx,SanketDG/networkx,jakevdp/networkx,ionanrozenfeld/networkx,dhimmel/networkx,yashu-seth/networkx,aureooms/networkx,aureooms/networkx,kernc/networkx,jcurbelo/networkx,sharifulgeo/networkx,nathania/networkx,ghdk/networkx,jakevdp/networkx,sharifulgeo/networkx,RMKD/networkx,andnovar/networkx,chrisnatali/networkx,debsankha/networkx,kernc/networkx,jfinkels/networkx,jni/networkx,chrisnatali/networkx,bzero/networkx,dhimmel/networkx,ghdk/networkx,chrisnatali/networkx,tmilicic/networkx,kernc/networkx,farhaanbukhsh/networkx,bzero/networkx,nathania/networkx,beni55/networkx,OrkoHunter/networkx,aureooms/networkx,RMKD/networkx,debsankha/networkx,harlowja/networkx,debsankha/networkx,blublud/networkx,JamesClough/networkx,nathania/networkx,dmoliveira/networkx,RMKD/networkx