Fix redundancies in test_morphism.
Fix redundancies in test_morphism.

I have been adding tests incrementally, which resulted in some mess and
redundancy in test_morphism.

dqnykamp/sympy,kaichogami/sympy,jerli/sympy,farhaanbukhsh/sympy,chaffra/sympy,skidzo/sympy,toolforger/sympy,MechCoder/sympy,sahilshekhawat/sympy,kumarkrishna/sympy,debugger22/sympy,Shaswat27/sympy,beni55/sympy,Titan-C/sympy,shikil/sympy,shikil/sympy,madan96/sympy,dqnykamp/sympy,pbrady/sympy,mafiya69/sympy,pandeyadarsh/sympy,Titan-C/sympy,lindsayad/sympy,kevalds51/sympy,cswiercz/sympy,jbbskinny/sympy,wyom/sympy,madan96/sympy,saurabhjn76/sympy,hargup/sympy,sunny94/temp,wyom/sympy,jaimahajan1997/sympy,kmacinnis/sympy,dqnykamp/sympy,AkademieOlympia/sympy,pandeyadarsh/sympy,hrashk/sympy,sahilshekhawat/sympy,kevalds51/sympy,iamutkarshtiwari/sympy,atsao72/sympy,maniteja123/sympy,Mitchkoens/sympy,amitjamadagni/sympy,pbrady/sympy,mcdaniel67/sympy,Shaswat27/sympy,kaichogami/sympy,wanglongqi/sympy,Shaswat27/sympy,flacjacket/sympy,Mitchkoens/sympy,pbrady/sympy,abhiii5459/sympy,wanglongqi/sympy,Curious72/sympy,abloomston/sympy,souravsingh/sympy,jamesblunt/sympy,sampadsaha5/sympy,kumarkrishna/sympy,vipulroxx/sympy,sahmed95/sympy,postvakje/sympy,chaffra/sympy,yukoba/sympy,sunny94/temp,kmacinnis/sympy,asm666/sympy,drufat/sympy,jamesblunt/sympy,kaushik94/sympy,Sumith1896/sympy,Arafatk/sympy,abloomston/sympy,hrashk/sympy,Vishluck/sympy,meghana1995/sympy,hargup/sympy,postvakje/sympy,Curious72/sympy,Davidjohnwilson/sympy,toolforger/sympy,sampadsaha5/sympy,ga7g08/sympy,Designist/sympy,beni55/sympy,ChristinaZografou/sympy,srjoglekar246/sympy,shipci/sympy,sahmed95/sympy,oliverlee/sympy,jaimahajan1997/sympy,Vishluck/sympy,jerli/sympy,mafiya69/sympy,sunny94/temp,rahuldan/sympy,ga7g08/sympy,grevutiu-gabriel/sympy,kaichogami/sympy,abhiii5459/sympy,mcdaniel67/sympy,lidavidm/sympy,MridulS/sympy,AkademieOlympia/sympy,skidzo/sympy,Mitchkoens/sympy,AunShiLord/sympy,Gadal/sympy,farhaanbukhsh/sympy,VaibhavAgarwalVA/sympy,liangjiaxing/sympy,yukoba/sympy,jerli/sympy,Davidjohnwilson/sympy,atreyv/sympy,jbbskinny/sympy,abhiii5459/sympy,ChristinaZografou/sympy,postvakje/sympy,Sumith1896/sympy,diofant/diofant,lidavidm/sympy,pandeyadarsh/sympy,saurabhjn76/sympy,souravsingh/sympy,liangjiaxing/sympy,iamutkarshtiwari/sympy,MridulS/sympy,toolforger/sympy,emon10005/sympy,Designist/sympy,rahuldan/sympy,hrashk/sympy,sahilshekhawat/sympy,debugger22/sympy,cswiercz/sympy,Designist/sympy,Arafatk/sympy,yukoba/sympy,asm666/sympy,vipulroxx/sympy,moble/sympy,asm666/sympy,aktech/sympy,chaffra/sympy,meghana1995/sympy,farhaanbukhsh/sympy,VaibhavAgarwalVA/sympy,lindsayad/sympy,garvitr/sympy,atreyv/sympy,aktech/sympy,garvitr/sympy,hargup/sympy,lidavidm/sympy,kaushik94/sympy,rahuldan/sympy,bukzor/sympy,kaushik94/sympy,MechCoder/sympy,atsao72/sympy,yashsharan/sympy,shipci/sympy,Davidjohnwilson/sympy,ga7g08/sympy,VaibhavAgarwalVA/sympy,Curious72/sympy,Arafatk/sympy,cccfran/sympy,meghana1995/sympy,jbbskinny/sympy,wanglongqi/sympy,iamutkarshtiwari/sympy,souravsingh/sympy,drufat/sympy,mafiya69/sympy,jaimahajan1997/sympy,wyom/sympy,Sumith1896/sympy,AunShiLord/sympy,saurabhjn76/sympy,kevalds51/sympy,lindsayad/sympy,kumarkrishna/sympy,Gadal/sympy,aktech/sympy,maniteja123/sympy,bukzor/sympy,mcdaniel67/sympy,ahhda/sympy,MridulS/sympy,vipulroxx/sympy,cccfran/sympy,ahhda/sympy,Titan-C/sympy,beni55/sympy,yashsharan/sympy,sahmed95/sympy,atreyv/sympy,debugger22/sympy,shikil/sympy,moble/sympy,amitjamadagni/sympy,oliverlee/sympy,jamesblunt/sympy,madan96/sympy,abloomston/sympy,bukzor/sympy,garvitr/sympy,skirpichev/omg,yashsharan/sympy,drufat/sympy,sampadsaha5/sympy,liangjiaxing/sympy,ChristinaZografou/sympy,MechCoder/sympy,cswiercz/sympy,emon10005/sympy,cccfran/sympy,skidzo/sympy,AunShiLord/sympy,Vishluck/sympy,ahhda/sympy,AkademieOlympia/sympy,grevutiu-gabriel/sympy,Gadal/sympy,shipci/sympy,moble/sympy,kmacinnis/sympy,maniteja123/sympy,grevutiu-gabriel/sympy,emon10005/sympy,atsao72/sympy,oliverlee/sympy