py/objset: Fix inplace binary ops so frozensets are not modified.
py/objset: Fix inplace binary ops so frozensets are not modified.

tralamazza/micropython,trezor/micropython,MrSurly/micropython-esp32,Timmenem/micropython,torwag/micropython,AriZuu/micropython,cwyark/micropython,cwyark/micropython,AriZuu/micropython,cwyark/micropython,alex-robbins/micropython,micropython/micropython-esp32,infinnovation/micropython,Timmenem/micropython,micropython/micropython-esp32,lowRISC/micropython,ryannathans/micropython,PappaPeppar/micropython,tobbad/micropython,Peetz0r/micropython-esp32,ryannathans/micropython,MrSurly/micropython-esp32,SHA2017-badge/micropython-esp32,kerneltask/micropython,pramasoul/micropython,TDAbboud/micropython,lowRISC/micropython,PappaPeppar/micropython,kerneltask/micropython,pozetroninc/micropython,pozetroninc/micropython,HenrikSolver/micropython,blazewicz/micropython,hiway/micropython,MrSurly/micropython-esp32,henriknelson/micropython,puuu/micropython,alex-robbins/micropython,pramasoul/micropython,tobbad/micropython,pfalcon/micropython,trezor/micropython,bvernoux/micropython,bvernoux/micropython,kerneltask/micropython,SHA2017-badge/micropython-esp32,pfalcon/micropython,swegener/micropython,tralamazza/micropython,pozetroninc/micropython,deshipu/micropython,pramasoul/micropython,mhoffma/micropython,pramasoul/micropython,PappaPeppar/micropython,oopy/micropython,Peetz0r/micropython-esp32,toolmacher/micropython,Peetz0r/micropython-esp32,micropython/micropython-esp32,TDAbboud/micropython,mhoffma/micropython,infinnovation/micropython,chrisdearman/micropython,Timmenem/micropython,mhoffma/micropython,bvernoux/micropython,torwag/micropython,MrSurly/micropython,mhoffma/micropython,Timmenem/micropython,puuu/micropython,oopy/micropython,adafruit/circuitpython,pozetroninc/micropython,pfalcon/micropython,MrSurly/micropython,toolmacher/micropython,TDAbboud/micropython,selste/micropython,lowRISC/micropython,pfalcon/micropython,PappaPeppar/micropython,swegener/micropython,trezor/micropython,adafruit/circuitpython,infinnovation/micropython,alex-robbins/micropython,tralamazza/micropython,selste/micropython,AriZuu/micropython,adafruit/circuitpython,swegener/micropython,AriZuu/micropython,puuu/micropython,micropython/micropython-esp32,oopy/micropython,pozetroninc/micropython,adafruit/circuitpython,HenrikSolver/micropython,blazewicz/micropython,selste/micropython,cwyark/micropython,dmazzella/micropython,infinnovation/micropython,MrSurly/micropython-esp32,puuu/micropython,Peetz0r/micropython-esp32,blazewicz/micropython,trezor/micropython,mhoffma/micropython,deshipu/micropython,torwag/micropython,MrSurly/micropython,dmazzella/micropython,alex-robbins/micropython,MrSurly/micropython-esp32,infinnovation/micropython,adafruit/micropython,AriZuu/micropython,HenrikSolver/micropython,torwag/micropython,tobbad/micropython,trezor/micropython,dmazzella/micropython,adafruit/micropython,tobbad/micropython,alex-robbins/micropython,bvernoux/micropython,TDAbboud/micropython,HenrikSolver/micropython,toolmacher/micropython,bvernoux/micropython,adafruit/circuitpython,pramasoul/micropython,SHA2017-badge/micropython-esp32,HenrikSolver/micropython,Timmenem/micropython,torwag/micropython,lowRISC/micropython,dmazzella/micropython,Peetz0r/micropython-esp32,SHA2017-badge/micropython-esp32,SHA2017-badge/micropython-esp32,henriknelson/micropython,chrisdearman/micropython,ryannathans/micropython,adafruit/circuitpython,adafruit/micropython,pfalcon/micropython,MrSurly/micropython,PappaPeppar/micropython,hiway/micropython,chrisdearman/micropython,kerneltask/micropython,puuu/micropython,hiway/micropython,ryannathans/micropython,henriknelson/micropython,oopy/micropython,selste/micropython,henriknelson/micropython,adafruit/micropython,chrisdearman/micropython,toolmacher/micropython,selste/micropython,kerneltask/micropython,ryannathans/micropython,MrSurly/micropython,deshipu/micropython,tralamazza/micropython,lowRISC/micropython,oopy/micropython,cwyark/micropython,blazewicz/micropython,tobbad/micropython,toolmacher/micropython,adafruit/micropython,TDAbboud/micropython,hiway/micropython,micropython/micropython-esp32,swegener/micropython,deshipu/micropython,deshipu/micropython,chrisdearman/micropython,hiway/micropython,blazewicz/micropython,swegener/micropython,henriknelson/micropython