HANG timeout on win32.fiber-rac

Failed on a master merge: https://github.com/DynamoRIO/dynamorio/runs/2221758433?check_suite_focus=true

test 27
        Start  27: code_api|win32.fiber-rac

27: Test command: D:\a\dynamorio\dynamorio\build_debug-internal-64\bin64\drrun.exe "-s" "90" "-quiet" "-debug" "-use_dll" "D:/a/dynamorio/dynamorio/build_debug-internal-64/lib64/debug/dynamorio.dll" "-exit0" "-stderr_mask" "0xC" "-msgbox_mask" "0" "-dumpcore_mask" "0x7d" "-staged" "-code_api" "--" "D:/a/dynamorio/dynamorio/build_debug-internal-64/suite/tests/bin/win32.fiber-rac.exe"
27: Test timeout computed to be: 600
 69/257 Test  #27: code_api|win32.fiber-rac .....................................***Failed  Required regular expression not found. Regex=[^in main thread
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main thread converted to fiber
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creating worker fiber 0
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switching to worker fiber first time
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in worker fiber
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back to main
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switching to worker fiber second time
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in worker fiber again
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deleting worker fiber 0
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creating worker fiber 1
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switching to worker fiber first time
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in worker fiber
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back to main
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switching to worker fiber second time
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in worker fiber again
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deleting worker fiber 1
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all done
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$
] 90.03 sec