shutdownCapability sometimes loops indefinitely on OSX after hs_exit()
Issue #9284 (closed) relates to
forkProcess, which previously invoked the same code that is invoked by
hs_exit and uncovered this problem. The resolution of #9284 (closed) is to not invoke the equivalent of
hs_exit (for reasons that you can see in #9284 (closed)). However,
hs_exit can be called by programs that explicitly create and teardown a Haskell runtime, so the problem displayed by #9284 (closed) can still occur for those programs.
The problem has only been observed on OS X, though it probably could occur on Linux OSes as well.