Is AsyncThrowingStream thread safe?

[paulz]

When we write to the stream and read from multiple threads we see thread sanitizer warnings:

SUMMARY: ThreadSanitizer: data race AsyncSequencePublisher.swift in (1) await resume partial function for closure #1 in ...
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ThreadSanitizer report breakpoint hit. Use 'thread info -s' to get extended information about the report.
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WARNING: ThreadSanitizer: data race (pid=26261)
  Read of size 8 at 0x7b6400030cf0 by thread T4:
    #0 (1) await resume partial function for closure #1 in static ...
    #1 swift::runJobInEstablishedExecutorContext(swift::Job*) <null>:2 (libswift_Concurrency.dylib:x86_64+0x2a4b5)

  Previous write of size 8 at 0x7b6400030cf0 by thread T3:
    #0 closure #1 in ... 
    #1 swift::runJobInEstablishedExecutorContext(swift::Job*) <null>:2 (libswift_Concurrency.dylib:x86_64+0x2a4b5)

  Location is heap block of size 1032 at 0x7b6400030c00 allocated by thread T3:
    #0 malloc <null>:2 (libclang_rt.tsan_iossim_dynamic.dylib:x86_64+0x533ac)
    #1 swift::StackAllocator<1000ul, &(swift::TaskAllocatorSlabMetadata)>::getSlabForAllocation(unsigned long) <null>:2 (libswift_Concurrency.dylib:x86_64+0x2f19a)
    #2 swift::runJobInEstablishedExecutorContext(swift::Job*) <null>:2 (libswift_Concurrency.dylib:x86_64+0x2a4b5)