fix inheritance of _doctest_depends_on attr in Circle class
fix inheritance of _doctest_depends_on attr in Circle class

Set the _doctest_depends_on attr of the Circle class to an empty dict
because otherwise the inherited non empty dict of the Ellipse base class
would be used instead.

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