bug() {
	trap : exit
	# Bug was causing sh to be run in subshell,
	# as if this line is replaced with (sh -c ...; exit $?) &
	# here:
	sh -c 'echo REAL_CHILD=$$' &
	echo PARENTS_IDEA_OF_CHILD=$!
	wait  # make sure bkgd shell completes
}

bug | {
while read varval; do
	eval $varval
done
test x"$REAL_CHILD" != x"" \
&& test x"$REAL_CHILD" = x"$PARENTS_IDEA_OF_CHILD"
echo "Bug detected: $?"
}
