testwsdeque passed unexpected in unregisterised job

This run of the unreg job saw an unexpected pass of the testwsdeque test in the threaded1 way:

=====> testwsdeque(threaded1) 4524 of 7230 [0, 0, 0]
cd "rts/testwsdeque.run" &&  "/builds/ghc/ghc/inplace/bin/ghc-stage2" -o testwsdeque testwsdeque.c -dcore-lint -dstg-lint -dcmm-lint -no-user-package-db -rtsopts -optc-fno-builtin -fno-warn-missed-specialisations -fshow-warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -Werror=compat -dno-debug-output  -threaded -debug  -no-hs-main < 
cd "rts/testwsdeque.run" && ./testwsdeque  < 
*** unexpected pass for testwsdeque(threaded1)

It is expected to fail due to req_smp apparently due to the need for atomic cas.