fix KroneckerDelta not canonical (issue 3479) and added new test
fix KroneckerDelta not canonical (issue 3479) and added new test

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