Virtualenv: 无法创建python 2.7环境

问题

在 Ubuntu 18.04 docker 环境中，tox 正在尝试执行virtualenv --no-download --python /usr/bin/python2.7 py27 。 使用 virtualenv 20.0.10 这有效。 从 20.0.11 开始，此操作失败并出现错误：

TypeError: unsupported operand type(s) for /: 'tuple' and 'str'

它应该仍然有效。

环境

至少提供：

• 操作系统：Ubuntu 18.04
• pip list安装了virtualenv的宿主 python：

Package                       Version              Location                     
----------------------------- -------------------- ----------------------------------
amqp                          2.5.2
appdirs                       1.4.3
attrs                         19.3.0
bcrypt                        3.1.7
billiard                      3.6.3.0
bleach                        3.1.3
boto3                         1.12.24
botocore                      1.15.24
cachetools                    4.0.0
celery                        4.4.2
certifi                       2019.11.28
cffi                          1.14.0
chardet                       3.0.4
cheroot                       8.3.0
CherryPy                      18.5.0
click                         7.1.1
click-plugins                 1.1.1
cryptography                  2.8
ctk-cli                       1.5
decorator                     4.4.2
diskcache                     4.1.0
distlib                       0.3.0
docker                        4.2.0
docutils                      0.15.2
dogpile.cache                 0.9.0
filelock                      3.0.12
fusepy                        3.0.1
GDAL                          3.1.0
girder                        3.0.11               /opt/girder                  
girder-archive-access         0.2.0
girder-client                 3.0.11               /opt/girder/clients/python   
girder-dicom-viewer           3.0.11
girder-homepage               3.0.11
girder-jobs                   3.0.11
girder-large-image            1.0.5.dev13+gc67ca6f /opt/large_image/girder      
girder-large-image-annotation 1.0.5.dev13+gc67ca6f /opt/large_image/girder_annotation
girder-ldap                   3.0.11
girder-resource-path-tools    1.0.1.dev2
girder-slicer-cli-web         1.0.2.dev28+g9db4a50 /opt/slicer_cli_web          
girder-virtual-folders        3.0.11
girder-worker                 0.6.1.dev23+g5810d1d /opt/girder_worker           
girder-worker-utils           0.8.7.dev2+g856849e  /opt/girder_worker_utils     
girder-xtk-demo               0.4.0
Glymur                        0.9.1
histomicsui                   1.0.0.dev39+ga7d0e3f /opt/HistomicsUI             
idna                          2.9
importlib-metadata            1.5.0
importlib-resources           1.4.0
jaraco.classes                3.1.0
jaraco.collections            3.0.0
jaraco.functools              3.0.0
jaraco.text                   3.2.0
jeepney                       0.4.3
Jinja2                        2.11.1
jmespath                      0.9.5
jsonpickle                    1.3
jsonschema                    3.2.0
keyring                       21.2.0
kombu                         4.6.8
large-image                   1.0.5.dev13+gc67ca6f /opt/large_image             
large-image-source-dummy      1.0.5.dev13+gc67ca6f /opt/large_image/sources/dummy
large-image-source-gdal       1.0.5.dev13+gc67ca6f /opt/large_image/sources/gdal
large-image-source-mapnik     1.0.5.dev13+gc67ca6f /opt/large_image/sources/mapnik
large-image-source-nd2        1.0.5.dev13+gc67ca6f /opt/large_image/sources/nd2 
large-image-source-ometiff    1.0.5.dev13+gc67ca6f /opt/large_image/sources/ometiff
large-image-source-openjpeg   1.0.5.dev13+gc67ca6f /opt/large_image/sources/openjpeg
large-image-source-openslide  1.0.5.dev13+gc67ca6f /opt/large_image/sources/openslide
large-image-source-pil        1.0.5.dev13+gc67ca6f /opt/large_image/sources/pil 
large-image-source-test       1.0.5.dev13+gc67ca6f /opt/large_image/sources/test
large-image-source-tiff       1.0.5.dev13+gc67ca6f /opt/large_image/sources/tiff
large-image-tasks             1.0.5.dev13+gc67ca6f /opt/large_image/tasks       
libtiff                       0.5.0
lxml                          4.5.0
Mako                          1.1.2
mapnik                        4.0.0
MarkupSafe                    1.1.1
more-itertools                8.2.0
nd2reader                     3.2.3
numpy                         1.18.2
openslide-python              1.1.1
packaging                     20.3
palettable                    3.3.0
passlib                       1.7.2
pbr                           5.4.4
Pillow                        7.0.0
PIMS                          0.4.1
pip                           20.0.2
pkg-resources                 0.0.0
pkgconfig                     1.5.1
pkginfo                       1.5.0.1
pluggy                        0.13.1
portend                       2.6
psutil                        5.7.0
py                            1.8.1
pyasn1                        0.4.8
pyasn1-modules                0.2.8
pycparser                     2.20
pydicom                       1.4.2
Pygments                      2.6.1
pyldap                        3.0.0.post1
pylibmc                       1.6.1
pymongo                       3.10.1
pyOpenSSL                     19.1.0
pyparsing                     2.4.6
pyproj                        2.6.0
pyrsistent                    0.15.7
python-dateutil               2.8.1
python-ldap                   3.2.0
pytz                          2019.3
pyvips                        2.1.12
PyYAML                        5.3.1
readme-renderer               25.0
requests                      2.23.0
requests-toolbelt             0.9.1
s3transfer                    0.3.3
SecretStorage                 3.1.2
setuptools                    46.0.0
setuptools-scm                3.5.0
six                           1.14.0
slicerator                    1.0.0
stevedore                     1.32.0
tempora                       2.1.0
toml                          0.10.0
tox                           3.14.5
tqdm                          4.43.0
twine                         3.1.1
ujson                         2.0.2
urllib3                       1.25.8
vine                          1.3.0
virtualenv                    20.0.12
webencodings                  0.5.1
websocket-client              0.57.0
xmltodict                     0.12.0
zc.lockfile                   2.0
zipp                          3.1.0

虚拟环境创建的输出

确保使用-vvv --with-traceback运行创建：

306 setup logging to NOTSET [DEBUG report:43]
375 find interpreter for spec PythonSpec(path=/usr/bin/python2.7) [INFO builtin:44]
377 Attempting to acquire lock 139669810685880 on /home/ubuntu/.local/share/virtualenv/py_info/20.0.12/beb4f305451b4835b36a63cb1c75e625a7251cf8d76b65be2f5856eee68cb551.lock [DEBUG filelock:270]
378 Lock 139669810685880 acquired on /home/ubuntu/.local/share/virtualenv/py_info/20.0.12/beb4f305451b4835b36a63cb1c75e625a7251cf8d76b65be2f5856eee68cb551.lock [INFO filelock:274]
378 get PythonInfo from /home/ubuntu/.local/share/virtualenv/py_info/20.0.12/beb4f305451b4835b36a63cb1c75e625a7251cf8d76b65be2f5856eee68cb551.json for /usr/bin/python2.7 [DEBUG cached_py_info:79]
379 Attempting to release lock 139669810685880 on /home/ubuntu/.local/share/virtualenv/py_info/20.0.12/beb4f305451b4835b36a63cb1c75e625a7251cf8d76b65be2f5856eee68cb551.lock [DEBUG filelock:315]
380 Lock 139669810685880 released on /home/ubuntu/.local/share/virtualenv/py_info/20.0.12/beb4f305451b4835b36a63cb1c75e625a7251cf8d76b65be2f5856eee68cb551.lock [INFO filelock:318]
380 proposed PythonInfo(spec=CPython2.7.17.final.0-64, exe=/usr/bin/python2.7, platform=linux2, version='2.7.17 (default, Nov  7 2019, 10:07:09) \n[GCC 7.4.0]', encoding_fs_io=UTF-8-None) [INFO builtin:50]
380 accepted PythonInfo(spec=CPython2.7.17.final.0-64, exe=/usr/bin/python2.7, platform=linux2, version='2.7.17 (default, Nov  7 2019, 10:07:09) \n[GCC 7.4.0]', encoding_fs_io=UTF-8-None) [DEBUG builtin:52]
383 filesystem is case-sensitive [DEBUG info:28]
Traceback (most recent call last):
  File "/usr/lib/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/__main__.py", line 62, in <module>
    run_with_catch()
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/__main__.py", line 51, in run_with_catch
    run(args, options)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/__main__.py", line 20, in run
    session = cli_run(args, options)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/run/__init__.py", line 27, in cli_run
    session = session_via_cli(args, options)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/run/__init__.py", line 35, in session_via_cli
    parser = build_parser(args, options)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/run/__init__.py", line 75, in build_parser
    CreatorSelector(interpreter, parser),
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/run/plugin/creators.py", line 15, in __init__
    creators, self.key_to_meta, self.describe, self.builtin_key = self.for_interpreter(interpreter)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/run/plugin/creators.py", line 25, in for_interpreter
    meta = creator_class.can_create(interpreter)
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/create/via_global_ref/builtin/via_global_self_do.py", line 33, in can_create
    for src in cls.sources(interpreter):
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/create/via_global_ref/builtin/cpython/cpython2.py", line 66, in sources
    for src in super(CPython2Posix, cls).sources(interpreter):
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/create/via_global_ref/builtin/cpython/cpython2.py", line 21, in sources
    for src in super(CPython2, cls).sources(interpreter):
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/create/via_global_ref/builtin/python2/python2.py", line 76, in sources
    compiled_file, to_compiled, compiled_exists = cls.from_stdlib(mappings, "{}.pyc".format(req))
  File "/home/ubuntu/.virtualenvs/girder/lib/python3.6/site-packages/virtualenv/create/via_global_ref/builtin/python2/python2.py", line 88, in from_stdlib
    result = (mappings[0] / name, mappings[1], False)
TypeError: unsupported operand type(s) for /: 'tuple' and 'str'

具体错误看起来像是在https://github.com/pypa/virtualenv/blob/master/src/virtualenv/create/via_global_ref/builtin/python2/python2.py#L79 -L85 的 #1728 中引入的。 具体来说，这一行（https://github.com/pypa/virtualenv/blob/master/src/virtualenv/create/via_global_ref/builtin/python2/python2.py#L85）

        return mappings[0] / name, mappings[1], False

应该是

        return mappings[0][0] / name, mappings[0][1], False

因为映射是一个元组列表。