Simple program trips checkNurserySanity()

Error:

Repro: internal error: ASSERTION FAILED: file rts/sm/Sanity.c, line 713

    (GHC version 8.3.20170606 for x86_64_unknown_linux)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Repro steps:

• Add GhcRTSWays += thr_debug to mk/build.mk to build threaded debug runtime

inplace/bin/ghc-stage2 -fforce-recomp -debug -rtsopts -threaded -main-is Repro Repro.hs
./Repro +RTS -A16m -DS

Trac metadata

Trac field	Value
Version	8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	simonmar
Operating system
Architecture