Fixing bugs in expr.py with priorities.
Fixing bugs in expr.py with priorities.

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