Test for x*unknown -> unknown.__rmul__ is called  (#677)
Test for x*unknown -> unknown.__rmul__ is called  (#677)

This was fixed sometime ago, but's let write a test for it so we'll be sure it
works.

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