It seems like paygen is not able to find lock flag file 

Log snippet
0:10:52: INFO: Applying delta payload and verifying result
00:12:20: INFO: RunCommand: /b/c/cbuild/repository/.cache/common/gsutil_4.27.tar.gz/gsutil/gsutil -o 'Boto:num_retries=10' -h x-goog-if-generation-match:1512373913013081 rm gs://chromeos-releases/dev-channel/auron-paine/10176.3.0/payloads/LOCK_flag
00:12:20: ERROR: Failed: Build definition (board=u'auron-paine', version='10176.3.0', channel='dev-channel')
00:12:20: INFO: RunCommand: /b/c/cbuild/repository/.cache/common/gsutil_4.27.tar.gz/gsutil/gsutil rm -R gs://chromeos-releases/dev-channel/auron-paine/10176.3.0/payloads/signing
00:12:21: ERROR: <type 'exceptions.OSError'>: [Errno 2] No such file or directory
Traceback (most recent call last):
  File "/b/c/cbuild/repository/chromite/lib/parallel.py", line 603, in TaskRunner
    task(*x, **task_kwargs)
  File "/b/c/cbuild/repository/chromite/lib/parallel.py", line 801, in <lambda>
    fn = lambda idx, task_args: out_queue.put((idx, task(*task_args)))
  File "/b/c/cbuild/repository/chromite/lib/paygen/paygen_build_lib.py", line 249, in _GenerateSinglePayload
    dry_run=dry_run)
  File "/b/c/cbuild/repository/chromite/lib/paygen/paygen_payload_lib.py", line 828, in CreateAndUploadPayload
    dry_run=dry_run).Run()
  File "/b/c/cbuild/repository/chromite/lib/paygen/paygen_payload_lib.py", line 708, in Run
    self._drm(self._VerifyPayload)
  File "/b/c/cbuild/repository/chromite/lib/paygen/dryrun_lib.py", line 46, in __call__
    return self.Run(func, *args, **kwargs)
  File "/b/c/cbuild/repository/chromite/lib/paygen/dryrun_lib.py", line 83, in Run
    return self._Call(func, *args, **kwargs)
  File "/b/c/cbuild/repository/chromite/lib/paygen/dryrun_lib.py", line 87, in _Call
    return func(*args, **kwargs)
  File "/b/c/cbuild/repository/chromite/lib/paygen/paygen_payload_lib.py", line 682, in _VerifyPayload
    self._ApplyPayload(payload, is_delta)
  File "/b/c/cbuild/repository/chromite/lib/paygen/paygen_payload_lib.py", line 642, in _ApplyPayload
    payload.Apply(bspatch_path=bspatch_path, **part_files)
  File "/b/c/cbuild/repository/src/aosp/system/update_engine/scripts/update_payload/payload.py", line 321, in Apply
    old_rootfs_part=old_rootfs_part)
  File "/b/c/cbuild/repository/src/aosp/system/update_engine/scripts/update_payload/applier.py", line 627, in Run
    self.payload.manifest.old_rootfs_info)
  File "/b/c/cbuild/repository/src/aosp/system/update_engine/scripts/update_payload/applier.py", line 575, in _ApplyToPartition
    new_part_file, new_part_info.size)
  File "/b/c/cbuild/repository/src/aosp/system/update_engine/scripts/update_payload/applier.py", line 525, in _ApplyOperations
    new_part_file)
  File "/b/c/cbuild/repository/src/aosp/system/update_engine/scripts/update_payload/applier.py", line 426, in _ApplyDiffOperation
    subprocess.check_call(puffpatch_cmd)
  File "/usr/lib/python2.7/subprocess.py", line 535, in check_call
    retcode = call(*popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 522, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
    raise child_exception


full log: https://logs.chromium.org/v/?s=chromeos%2Fbb%2Fchromeos_release%2Fauron_paine-release_release-R64-10176.B%2F2%2F%2B%2Frecipes%2Fsteps%2FPaygenBuildDev%2F0%2Fstdout

Seems like the same issue for all boards