【问题】yocto学习：ERROR: Execution of event handler ‘sstate

下载yocto的代码，编译时，报错如下：

$ bitbake core-image-minimal
Loading cache: 100% |##########################################################################################################| Time: 0:00:00
Loaded 1320 entries from dependency cache.
ERROR: Execution of event handler 'sstate_eventhandler2' failed
Traceback (most recent call last):
  File "/home/some-user/projects/melp/poky/meta/classes/sstate.bbclass", line 1015, in sstate_eventhandler2(e=):
                 for l in lines:
    >                (stamp, manifest, workdir) = l.split()
                     if stamp not in stamps:
ValueError: not enough values to unpack (expected 3, got 1)

ERROR: Command execution failed: Traceback (most recent call last):
  File "/home/some-user/projects/melp/poky/bitbake/lib/bb/command.py", line 101, in runAsyncCommand
    self.cooker.updateCache()
  File "/home/some-user/projects/melp/poky/bitbake/lib/bb/cooker.py", line 1658, in updateCache
    bb.event.fire(event, self.databuilder.mcdata[mc])
  File "/home/some-user/projects/melp/poky/bitbake/lib/bb/event.py", line 201, in fire
    fire_class_handlers(event, d)
  File "/home/some-user/projects/melp/poky/bitbake/lib/bb/event.py", line 124, in fire_class_handlers
    execute_handler(name, handler, event, d)
  File "/home/some-user/projects/melp/poky/bitbake/lib/bb/event.py", line 96, in execute_handler
    ret = handler(event)
  File "/home/some-user/projects/melp/poky/meta/classes/sstate.bbclass", line 1015, in sstate_eventhandler2
    (stamp, manifest, workdir) = l.split()
ValueError: not enough values to unpack (expected 3, got 1)

看起来它是python错误。有谁知道这是什么问题？我使用的是错误的版本吗？

以下是python --version 的输出

$ python --version
Python 2.7.12

删除tmp和sstate-cache目录，然后重试，编译OK