bitbake weirdness during -k world

[Graham Gower <graham.gower@gmail.com>]

I have a 1gb world.log file after running:
bitbake -k world | tee world.log

The build appears to have gotten about half way through (compared with
previous builds) and then begun infinitely repeating the following message.

Traceback (most recent call last):
  File "/home/grg/oe2/bitbake/lib/bb/server/none.py", line 128, in idle_commands
    retval = function(self, data, False)
  File "/home/grg/oe2/bitbake/lib/bb/cooker.py", line 716, in buildTargetsIdle
    retval = rq.execute_runqueue()
  File "/home/grg/oe2/bitbake/lib/bb/runqueue.py", line 877, in execute_runqueue
    self.execute_runqueue_internal()
  File "/home/grg/oe2/bitbake/lib/bb/runqueue.py", line 992, in execute_runqueue_internal
    self.build_pipes[pipe].read()
  File "/home/grg/oe2/bitbake/lib/bb/runqueue.py", line 1227, in read
    bb.event.fire_from_worker(self.queue[:index+8], self.d)
  File "/home/grg/oe2/bitbake/lib/bb/event.py", line 137, in fire_from_worker
    event = pickle.loads(event[7:-8])
  File "/usr/lib64/python2.6/pickle.py", line 1374, in loads
    return Unpickler(file).load()
  File "/usr/lib64/python2.6/pickle.py", line 858, in load
    dispatch[key](self)
  File "/usr/lib64/python2.6/pickle.py", line 966, in load_string
    raise ValueError, "insecure string pickle"
ValueError: insecure string pickle


I identified the location where the message begins and it is not possible
to link it to any other errors nor to a particular recipe. Context looks like this:

NOTE: Unpacking ../oe/sources/libAppleWM-1.4.0.tar.bz2 to /mnt/oe/tmp/work/mipsel-oe-linux/libapplewm-1_1.4.0-r9.0/
NOTE: package dhcpcd-1.3.22-pl4-r1: task do_install: Succeeded
NOTE:   /usr/share/ti/ti-biosutils-tree/packages/xdoc/external.png
NOTE:   /usr/share/ti/ti-biosutils-tree/packages/xdoc/Bullet.png
Traceback (most recent call last):
  File "/home/grg/oe2/bitbake/lib/bb/server/none.py", line 128, in idle_commands
    retval = function(self, data, False)
  File "/home/grg/oe2/bitbake/lib/bb/cooker.py", line 716, in buildTargetsIdle
    retval = rq.execute_runqueue()



FYI, i do have this stupidity in my local.conf:
PARALLEL_MAKE = "-j 12"
BB_NUMBER_THREADS = "12"


-Graham