qtest failures leave orphaned qemu processes hanging around

If a qtest test case fails, it leaves orphaned qemu processes hanging around. On Fedora 18 with qemu.git as of today ( Feb 26 2013), the  patch just forces a test failure

ps axwww | grep qemu | grep -v grep
$ make check-qtest-x86_64
  CC    tests/rtc-test.o
  LINK  tests/rtc-test
GTESTER check-qtest-x86_64

$ ps axwww | grep qemu | grep -v grep
$ patch -p1 < force-test-failure.patch
patching file tests/rtc-test.c

$ make check-qtest-x86_64
  CC    tests/rtc-test.o
  LINK  tests/rtc-test
GTESTER check-qtest-x86_64
**
ERROR:tests/rtc-test.c:256:bcd_check_time: assertion failed: (0)
GTester: last random seed: R02Sf2521dda395a2713128e0cbf86651a21
make: *** [check-qtest-x86_64] Error 1

$ ps axwww | grep qemu | grep -v grep
26258 pts/0    Sl     0:00 x86_64-softmmu/qemu-system-x86_64 -qtest unix:/tmp/qtest-26256.sock,nowait -qtest-log /dev/null -qmp unix:/tmp/qtest-26256.qmp,nowait -pidfile /tmp/qtest-26256.pid -machine accel=qtest -display none -rtc clock=vm

The problem is that an assertion failure in a test case causes the test program to exit(2) without hitting the qtest cleanup.