python - 按 "pip install --upgrade"升级 pip 和 scrapy 后出现 pip 错误

Question

将 debian 8(jessie) amd64 与 python 2.7.9 结合使用。我尝试了以下命令:

pip install --upgrade pip

pip install --upgrade scrapy

在那之后，我得到了以下 pip 错误

root@debian:~# pip
Traceback (most recent call last):
File "/usr/local/bin/pip", line 11, in <module>
load_entry_point('pip==8.1.2', 'console_scripts', 'pip')()
File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 567, in load_entry_point
return get_distribution(dist).load_entry_point(group, name)
File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2604, in load_entry_point
return ep.load()
File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2264, in load
return self.resolve()
File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2270, in resolve
module = __import__(self.module_name, fromlist=['__name__'], level=0)
File "/usr/local/lib/python2.7/dist-packages/pip/__init__.py", line 16, in <module>
from pip.vcs import git, mercurial, subversion, bazaar  # noqa
File "/usr/local/lib/python2.7/dist-packages/pip/vcs/mercurial.py", line 9, in <module>
from pip.download import path_to_url
File "/usr/local/lib/python2.7/dist-packages/pip/download.py", line 39, in <module>
from pip._vendor import requests, six
File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/__init__.py", line 53, in <module>
from .packages.urllib3.contrib import pyopenssl
File "/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/contrib/pyopenssl.py", line 54, in <module>
import OpenSSL.SSL
File "/usr/lib/python2.7/dist-packages/OpenSSL/__init__.py", line 8, in <module>
from OpenSSL import rand, crypto, SSL
File "/usr/lib/python2.7/dist-packages/OpenSSL/rand.py", line 11, in <module>
from OpenSSL._util import (
File "/usr/lib/python2.7/dist-packages/OpenSSL/_util.py", line 4, in <module>
binding = Binding()
File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/bindings/openssl/binding.py", line 89, in __init__
self._ensure_ffi_initialized()
File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/bindings/openssl/binding.py", line 113, in _ensure_ffi_initialized
libraries=libraries,
File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/bindings/utils.py", line 80, in build_ffi
extra_link_args=extra_link_args,
File "/usr/local/lib/python2.7/dist-packages/cffi/api.py", line 437, in verify
lib = self.verifier.load_library()
File "/usr/local/lib/python2.7/dist-packages/cffi/verifier.py", line 114, in load_library
return self._load_library()
File "/usr/local/lib/python2.7/dist-packages/cffi/verifier.py", line 225, in _load_library
return self._vengine.load_library()
File "/usr/local/lib/python2.7/dist-packages/cffi/vengine_cpy.py", line 174, in load_library
lst = list(map(self.ffi._get_cached_btype, lst))
File "/usr/local/lib/python2.7/dist-packages/cffi/api.py", line 409, in _get_cached_btype
BType = type.get_cached_btype(self, finishlist)
File "/usr/local/lib/python2.7/dist-packages/cffi/model.py", line 61, in get_cached_btype
BType = self.build_backend_type(ffi, finishlist)
File "/usr/local/lib/python2.7/dist-packages/cffi/model.py", line 507, in build_backend_type
base_btype = self.build_baseinttype(ffi, finishlist)
File "/usr/local/lib/python2.7/dist-packages/cffi/model.py", line 525, in build_baseinttype
% self._get_c_name())
cffi.api.CDefError: 'point_conversion_form_t' has no values explicitly defined: refusing to guess which integer type it is meant to be (unsigned/signed, int/long)

用谷歌搜索了几个类似的问题，cffi 或密码学可能会导致这个问题，但我找不到任何明确的方法来解决它。

Answer 1

今天遇到完全相同的错误，但情况不同。我怀疑这与 cryptography 模块有关。

对我有帮助的是安装特定版本的 cffi 包:

pip install cffi==1.7.0