Python Couchbase CFFI - `AssertionError：backend .__ version __ = __version __ [：3]）`

Question

完整错误文字：

No module named couchbase._libcouchbase
Traceback (most recent call last):
  File "app_main.py", line 75, in run_toplevel
  File "runtests.py", line 12, in <module>
    mod = __import__(t, globals(), locals(), ['suite'])
  File "/home/travis/build/ardydedase/pycouchbase/tests/test_pycouchbase.py", line 15, in <module>
    from pycouchbase.utils import *
  File "/home/travis/build/ardydedase/pycouchbase/pycouchbase/__init__.py", line 11, in <module>
    import couchbase_ffi as couchase
  File "/home/travis/virtualenv/pypy-2.5.0/site-packages/couchbase_ffi-0.2.0.0-py2.7-linux-x86_64.egg/couchbase_ffi/__init__.py", line 50, in <module>
    import couchbase_ffi._libcouchbase as _libcouchbase
  File "/home/travis/virtualenv/pypy-2.5.0/site-packages/couchbase_ffi-0.2.0.0-py2.7-linux-x86_64.egg/couchbase_ffi/_libcouchbase.py", line 3, in <module>
    from couchbase_ffi._cinit import get_handle
  File "/home/travis/virtualenv/pypy-2.5.0/site-packages/couchbase_ffi-0.2.0.0-py2.7-linux-x86_64.egg/couchbase_ffi/_cinit.py", line 13, in <module>
    ffi = FFI()
  File "/home/travis/virtualenv/pypy-2.5.0/site-packages/cffi/api.py", line 59, in __init__
    backend.__version__ == __version__[:3])
AssertionError

只有当我在Travis的PyPy构建中尝试import couchbase_ffi时才会发生这种情况：https://travis-ci.org/ardydedase/pycouchbase/jobs/76043402#L1663

详细说明：

我在我的requirements.txt couchbase-python-cffi：

中有这个

cffi==0.8.0
couchbase==2.0

看起来与包的不兼容问题。但不确定它的来源。