fixes factor(), separatevars(), combsimp() from Issue #6280
fixes factor(), separatevars(), combsimp() from Issue #6280

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