Try setting matplotlib.use("Agg") in test_travis.sh
Try setting matplotlib.use("Agg") in test_travis.sh

jerli/sympy,kaushik94/sympy,jaimahajan1997/sympy,kaichogami/sympy,aktech/sympy,rahuldan/sympy,Titan-C/sympy,aktech/sympy,Curious72/sympy,lindsayad/sympy,souravsingh/sympy,chaffra/sympy,hargup/sympy,lindsayad/sympy,Curious72/sympy,Curious72/sympy,kaichogami/sympy,lindsayad/sympy,chaffra/sympy,jerli/sympy,hargup/sympy,drufat/sympy,postvakje/sympy,yashsharan/sympy,skidzo/sympy,rahuldan/sympy,chaffra/sympy,drufat/sympy,souravsingh/sympy,sampadsaha5/sympy,jaimahajan1997/sympy,jaimahajan1997/sympy,hargup/sympy,madan96/sympy,jerli/sympy,sampadsaha5/sympy,rahuldan/sympy,Titan-C/sympy,postvakje/sympy,kaichogami/sympy,kaushik94/sympy,yashsharan/sympy,madan96/sympy,skidzo/sympy,madan96/sympy,drufat/sympy,aktech/sympy,souravsingh/sympy,Titan-C/sympy,mafiya69/sympy,sampadsaha5/sympy,mafiya69/sympy,ChristinaZografou/sympy,ChristinaZografou/sympy,skidzo/sympy,mafiya69/sympy,kaushik94/sympy,yashsharan/sympy,ChristinaZografou/sympy,postvakje/sympy