Clean Shared State fails with the following error message.

[build@yoctoBuilder build]$ bitbake -c cleansstate bison-native
Loading cache: 100% |#################################################################################| ETA:  00:00:00
Loaded 1138 entries from dependency cache.
WARNING: Host distribution could not be determined; you may possibly experience unexpected failures. It is recommended that you use a tested distribution.

Build Configuration:
BB_VERSION        = "1.15.3"
TARGET_ARCH       = "arm"
TARGET_OS         = "linux-gnueabi"
MACHINE           = "qemuarm"
DISTRO            = "poky"
DISTRO_VERSION    = "1.2+snapshot-20120727"
TUNE_FEATURES     = "armv5 dsp thumb arm926ejs"
TARGET_FPU        = "soft"
meta              
meta-yocto        = "master:fb53d69d9c726e6a663ea276cc440676e20f8326"

NOTE: Resolving any missing task queue dependencies
NOTE: Preparing runqueue
NOTE: Executing RunQueue Tasks
NOTE: Running task 1 of 2 (ID: 0, virtual:native:/mnt/storage/yoctoBuilds/poky-vanilla.git/meta/recipes-devtools/bison/bison_2.5.bb, do_clean)
NOTE: package bison-native-2.5-r2: task do_clean: Started
ERROR: Error executing a python function in /mnt/storage/yoctoBuilds/poky-vanilla.git/meta/recipes-devtools/bison/bison_2.5.bb:
OSError: [Errno 39] Directory not empty: '/mnt/storage/yoctoBuilds/poky-vanilla.git/build/tmp/work/x86_64-linux/bison-native-2.5-r2/temp'

ERROR: The stack trace of python calls that resulted in this exception/failure was:
ERROR:   File "do_clean", line 16, in <module>
ERROR: 
ERROR:   File "do_clean", line 6, in do_clean
ERROR: 
ERROR:   File "/mnt/storage/yoctoBuilds/poky-vanilla.git/meta/lib/oe/path.py", line 94, in remove
ERROR:     shutil.rmtree(name)
ERROR: 
ERROR:   File "/usr/lib/python2.7/shutil.py", line 245, in rmtree
ERROR:     rmtree(fullname, ignore_errors, onerror)
ERROR: 
ERROR:   File "/usr/lib/python2.7/shutil.py", line 254, in rmtree
ERROR:     onerror(os.rmdir, path, sys.exc_info())
ERROR: 
ERROR:   File "/usr/lib/python2.7/shutil.py", line 252, in rmtree
ERROR:     os.rmdir(path)
ERROR: 
ERROR: The code that was being executed was:
ERROR:      0012:    for f in (d.getVar('CLEANFUNCS', True) or '').split():
ERROR:      0013:        bb.build.exec_func(f, d)
ERROR:      0014:
ERROR:      0015:
ERROR:  *** 0016:do_clean(d)
ERROR:      0017:
ERROR: (file: 'do_clean', lineno: 16, function: <module>)
ERROR:      0002:def do_clean(d):
ERROR:      0003:    """clear the build and temp directories"""
ERROR:      0004:    dir = d.expand("/mnt/storage/yoctoBuilds/poky-vanilla.git/build/tmp/work/x86_64-linux/bison-native-2.5-r2")
ERROR:      0005:    bb.note("Removing " + dir)
ERROR:  *** 0006:    oe.path.remove(dir)
ERROR:      0007:
ERROR:      0008:    dir = "%s.*" % bb.data.expand(d.getVar('STAMP'), d)
ERROR:      0009:    bb.note("Removing " + dir)
ERROR:      0010:    oe.path.remove(dir)
ERROR: (file: 'do_clean', lineno: 6, function: do_clean)
ERROR: Function failed: do_clean
NOTE: package bison-native-2.5-r2: task do_clean: Failed
ERROR: Task 0 (virtual:native:/mnt/storage/yoctoBuilds/poky-vanilla.git/meta/recipes-devtools/bison/bison_2.5.bb, do_clean) failed with exit code '1'
NOTE: Tasks Summary: Attempted 1 tasks of which 0 didn't need to be rerun and 1 failed.
ERROR: An uncaught exception occured in runqueue, please see the failure below:

Summary: 1 task failed:
  virtual:native:/mnt/storage/yoctoBuilds/poky-vanilla.git/meta/recipes-devtools/bison/bison_2.5.bb, do_clean
Summary: There was 1 WARNING message shown.
Summary: There were 38 ERROR messages shown, returning a non-zero exit code.
[build@yoctoBuilder build]$ 

The drive is mounted as an NFS share and has the correct permissions for reading/writing. RP mentioned (as I understood it) that it looks like a race condition with building log files in temp, and then not being able to remove them in time before the python rmdir equivalent gets called.