As I mentioned above the best solution for this problem in the mean time is to use a host-based application firewall like Little Snitch or Lulu to deny the internet access of nsurlsessiond. You just need to create a rule to deny internet access for:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/libexec/nsurlsessiond
Check this screenshot to get an idea:
dropbox.com/s/rf3kzbbhsgre1on/nsurlsessiond-rule.png?dl=0
Topic:
Developer Tools & Services
SubTopic:
Xcode
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