pip package installation on linux CI is broken

[jdm]

The taskcluster basic CI on all PRs is giving this error today:

+ ./mach test-tidy --no-progress --all
"/repo/python/_virtualenv2.7/bin/python2.7" "-m" "pip" "install" "-I" "-r" "/repo/tests/wpt/web-platform-tests/tools/wptrunner/requirements.txt" failed with error code 1:
Output:
Collecting html5lib==1.0.1
  Downloading html5lib-1.0.1-py2.py3-none-any.whl (117 kB)
Collecting mozinfo==1.2.1
  Downloading mozinfo-1.2.1-py2.py3-none-any.whl (7.1 kB)
Collecting mozlog==6.0
  Downloading mozlog-6.0-py2.py3-none-any.whl (68 kB)
Collecting mozdebug==0.2
  Using cached mozdebug-0.2.0-py2.py3-none-any.whl (6.0 kB)
Collecting pillow==6.2.2
  Downloading Pillow-6.2.2-cp27-cp27mu-manylinux1_x86_64.whl (2.1 MB)
Collecting urllib3[secure]==1.25.9
  Downloading urllib3-1.25.9-py2.py3-none-any.whl (126 kB)
Collecting requests==2.23.0
  Downloading requests-2.23.0-py2.py3-none-any.whl (58 kB)
Collecting six==1.14.0
  Downloading six-1.14.0-py2.py3-none-any.whl (10 kB)
Collecting webencodings
  Downloading webencodings-0.5.1-py2.py3-none-any.whl (11 kB)
Collecting distro==1.4.0
  Using cached distro-1.4.0-py2.py3-none-any.whl (17 kB)
Processing /root/.cache/pip/wheels/7f/d9/c6/19632d599677910115e65645ac5ccfe1d647ac262b806f91a9/mozfile-2.1.0-py2.py3-none-any.whl
Collecting blessings>=1.3
  Downloading blessings-1.7-py2-none-any.whl (26 kB)
Collecting mozterm
  Using cached mozterm-1.0.0-py2.py3-none-any.whl (3.4 kB)
Collecting idna>=2.0.0; extra == "secure"
  Downloading idna-2.9-py2.py3-none-any.whl (58 kB)
Collecting certifi; extra == "secure"
  Using cached certifi-2020.4.5.1-py2.py3-none-any.whl (157 kB)
Collecting ipaddress; python_version == "2.7" and extra == "secure"
  Downloading ipaddress-1.0.23-py2.py3-none-any.whl (18 kB)
Collecting cryptography>=1.3.4; extra == "secure"
  Downloading cryptography-2.9.1.tar.gz (517 kB)
  Installing build dependencies: started
  Installing build dependencies: finished with status 'done'
  Getting requirements to build wheel: started
  Getting requirements to build wheel: finished with status 'done'
    Preparing wheel metadata: started
    Preparing wheel metadata: finished with status 'error'
Error:
DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. A future version of pip will drop support for Python 2.7. More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
    ERROR: Command errored out with exit status 1:
     command: /repo/python/_virtualenv2.7/bin/python2.7 /repo/python/_virtualenv2.7/local/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel /tmp/tmp2hbjtI
         cwd: /tmp/pip-install-mOAWXW/cryptography
    Complete output (4 lines):
    /usr/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'long_description_content_type'
      warnings.warn(msg)
    running dist_info
    error: 'egg_base' must be a directory name (got `/tmp/pip-modern-metadata-5gyGwb`)
    ----------------------------------------
ERROR: Command errored out with exit status 1: /repo/python/_virtualenv2.7/bin/python2.7 /repo/python/_virtualenv2.7/local/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel 

[jdm]

cryptography 2.9.1 was released just over an hour ago, so that's pretty suspicious.

[dralley]

pyca/cryptography#5212 (comment)

Should be fixed now.

[jdm]

Looks like this should be fixed now.