Set:

IMAGETEST = "qemu"

and then:

bitbake meta-toolchain

which results in a python stack trace:

Traceback (most recent call last):
  File "/media/build1/poky/bitbake/lib/bb/cooker.py", line 1145, in buildTargetsIdle(server=<ProcessServer(ProcessServer-1, started)>, rq=<bb.runqueue.RunQueue instance at 0x5e25830>, abort=False):
                 try:
    >                retval = rq.execute_runqueue()
                 except runqueue.TaskFailure as exc:
  File "/media/build1/poky/bitbake/lib/bb/runqueue.py", line 932, in RunQueue.execute_runqueue():
             try:
    >            return self._execute_runqueue()
             except bb.runqueue.TaskFailure:
  File "/media/build1/poky/bitbake/lib/bb/runqueue.py", line 876, in RunQueue._execute_runqueue():
                 self.rqexe = RunQueueExecuteDummy(self)
    >            if self.rqdata.prepare() == 0:
                     self.state = runQueueComplete
  File "/media/build1/poky/bitbake/lib/bb/runqueue.py", line 736, in RunQueueData.prepare():
                             procdep.append(self.taskData.fn_index[self.runq_fnid[dep]] + "." + self.runq_task[dep])
    >                    self.runq_hash[task] = bb.parse.siggen.get_taskhash(self.taskData.fn_index[self.runq_fnid[task]], self.runq_task[task], procdep, self.dataCache)
     
  File "/media/build1/poky/bitbake/lib/bb/siggen.py", line 172, in SignatureGeneratorOEBasicHash.get_taskhash(fn='/media/build1/poky/meta/recipes-core/meta/meta-toolchain.bb', task='do_rootfs', deps=[], dataCache=<bb.cache.CacheData object at 0x29a1a90>):
             k = fn + "." + task
    >        data = dataCache.basetaskhash[k]
             self.runtaskdeps[k] = []
KeyError: '/media/build1/poky/meta/recipes-core/meta/meta-toolchain.bb.do_rootfs'

NOTE: Tasks Summary: Attempted 0 tasks of which 0 didn't need to be rerun and all succeeded.