InstalledRepository load() breaks if there's an empty string for a env.sys_path variable

• [x ] I am on the latest Poetry version.
• [x ] I have searched the issues of this repo and believe that this is not a duplicate.
• [x ] If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: <Ubuntu 18.04.3>
• Poetry version: <1.0.0>

Issue

I ran into an error that pops up as: expected string or bytes-like object. I followed the stack trace and found the location where it happens: /.poetry/lib/poetry/repositories/installed_repository.py

The problem is in the load() function where it calls to get a list of paths or something using the env.sys_path variable. For me it looked like this:

‘’’ for distribution in sorted( metadata.distributions(path=env.sys_path), key=lambda d: str(d._path), ): ‘’’

But I know that this is a little different between versions, so I’ll specifically say that the issue was the env.sys_path. My env.sys_path was returning one string that’s empty in it’s list. I don’t know why, I just know it does that. The empty string then is passed along with the rest of the code which assumes that it is a distribution package with metadata. It specifically passes along a None value which then breaks things later. The load() function needs to have logic to handle the case where env.sys_path has an empty string in the return values.

I was able to fix it by adding a simple check after the values are returned:

            name = distribution.metadata["name"]
            if name is None:
                continue

I tried cleaning the names for env.sys_path before they’re used but then I get a different weird error:

[TypeError]
find_distributions() got an unexpected keyword argument 'name'

So I just did the simple fix where I check if name is None.

Simple fix, should be quick to add to the next release.

Stack trace:

[TypeError]
expected string or bytes-like object

Traceback (most recent call last):
  File "/home/.poetry/lib/poetry/_vendor/py3.6/clikit/console_application.py", line 131, in run
    status_code = command.handle(parsed_args, io)
  File "/home/.poetry/lib/poetry/_vendor/py3.6/clikit/api/command/command.py", line 120, in handle
    status_code = self._do_handle(args, io)
  File "/home/.poetry/lib/poetry/_vendor/py3.6/clikit/api/command/command.py", line 171, in _do_handle
    return getattr(handler, handler_method)(args, io, self)
  File "/home/.poetry/lib/poetry/_vendor/py3.6/cleo/commands/command.py", line 92, in wrap_handle
    return self.handle()
  File "/home/.poetry/lib/poetry/console/commands/install.py", line 48, in handle
    self.io, self.env, self.poetry.package, self.poetry.locker, self.poetry.pool
  File "/home/.poetry/lib/poetry/installation/installer.py", line 55, in __init__
    installed = self._get_installed()
  File "/home/.poetry/lib/poetry/installation/installer.py", line 488, in _get_installed
    return InstalledRepository.load(self._env)
  File "/home/.poetry/lib/poetry/repositories/installed_repository.py", line 24, in load
    package = Package(name, version, version)
  File "/home/.poetry/lib/poetry/packages/package.py", line 42, in __init__
    self._name = canonicalize_name(name)
  File "/home/.poetry/lib/poetry/utils/helpers.py", line 31, in canonicalize_name
    return _canonicalize_regex.sub('-', name).lower()

[sisp]

I’m experiencing the same issue when using tox. pip install tox now installs virtualenv==20.0.0, but a few days ago 16.7.9 was installed. Forcing virtualenv<20, i.e. pip install 'virtualenv<20' tox, solves the problem for me, but it’s only a quick fix.

[stefsmeets]

A simple work-around is to change https://github.com/python-poetry/poetry/blob/master/poetry/repositories/installed_repository.py#L25 to:

                name = distribution.metadata["name"]
                if not name:
                    continue