Loss of singleton type when pickling
Loss of singleton type when pickling

This commit documents the loss of the singleton type and its resulting inability te be used in exact operations after pickling and unpickling with protocol less than 2.

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