`poetry add` does not support paths without a directory component

• Poetry version: 1.2.2
• Python version: 3.8.10
• OS version and name: Windows 10
• pyproject.toml: N/A

• I am on the latest stable Poetry version, installed using a recommended method.
• I have searched the issues of this repo and believe that this is not a duplicate.
• I have consulted the FAQ and blog for any relevant entries or release notes.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option) and have included the output below.

Issue

poetry add my-wheel.whl results in the following error, however the same command poetry add ./my-wheel.whl works fine:

Using virtualenv: C:\Users\*\AppData\Local\pypoetry\Cache\virtualenvs\*-NWGIXhkQ-py3.8
 
  Stack trace:
 
  14  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\application.py:329 in run
       327│
       328│             try:
     → 329│                 exit_code = self._run(io)
       330│             except Exception as e:
       331│                 if not self._catch_exceptions:
 
  13  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\console\application.py:185 in _run
       183│         self._load_plugins(io)
       184│
     → 185│         exit_code: int = super()._run(io)
       186│         return exit_code
       187│
 
  12  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\application.py:423 in _run
       421│             io.input.set_stream(stream)
       422│
     → 423│         exit_code = self._run_command(command, io)
       424│         self._running_command = None
       425│
 
  11  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\application.py:465 in _run_command
       463│
       464│         if error is not None:
     → 465│             raise error
       466│
       467│         return event.exit_code
 
  10  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\application.py:449 in _run_command
       447│
       448│             if event.command_should_run():
     → 449│                 exit_code = command.run(io)
       450│             else:
       451│                 exit_code = ConsoleCommandEvent.RETURN_CODE_DISABLED
 
   9  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\commands\base_command.py:119 in run
       117│         io.input.validate()
       118│
     → 119│         status_code = self.execute(io)
       120│
       121│         if status_code is None:
 
   8  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\cleo\commands\command.py:83 in execute
        81│
        82│         try:
     →  83│             return self.handle()
        84│         except KeyboardInterrupt:
        85│             return 1
 
   7  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\console\commands\add.py:158 in handle
       156│             return 0
       157│
     → 158│         requirements = self._determine_requirements(
       159│             packages,
       160│             allow_prereleases=self.option("allow-prereleases"),
 
   6  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\console\commands\init.py:357 in _determine_requirements
       355│
       356│         result = []
     → 357│         for requirement in self._parse_requirements(requires):
       358│             if "git" in requirement or "url" in requirement or "path" in requirement:
       359│                 result.append(requirement)
 
   5  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\console\commands\init.py:416 in _parse_requirements
       414│             cwd = Path.cwd()
       415│
     → 416│         return [
       417│             parse_dependency_specification(
       418│                 requirement=requirement,
 
   4  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\console\commands\init.py:417 in <listcomp>
       415│
       416│         return [
     → 417│             parse_dependency_specification(
       418│                 requirement=requirement,
       419│                 env=self.env if isinstance(self, EnvCommand) else None,
 
   3  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\utils\dependency_specification.py:204 in parse_dependency_specification
       202│     cwd = cwd or Path.cwd()
       203│
     → 204│     specification = pep508_to_dependency_specification(requirement)
       205│
       206│     if specification is not None:
 
   2  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\utils\dependency_specification.py:187 in pep508_to_dependency_specification
       185│
       186│     with contextlib.suppress(ValueError):
     → 187│         dependency = Dependency.create_from_pep_508(requirement)
       188│         specification: DependencySpec = {}
       189│         specification = dependency_to_specification(dependency, specification)
 
   1  ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\core\packages\dependency.py:448 in create_from_pep_508
       446│             elif is_file_uri:
       447│                 # handle RFC 8089 references
     → 448│                 path = url_to_path(req.url)
       449│                 dep = _make_file_or_dir_dep(
       450│                     name=name, path=path, base=relative_to, extras=req.extras
 
  AttributeError
 
  'NoneType' object has no attribute 'startswith'
 
  at ~\AppData\Roaming\pypoetry\venv\lib\site-packages\poetry\core\packages\utils\utils.py:72 in url_to_path
       68│
       69│     The logic used here is borrowed from pip
       70│     https://github.com/pypa/pip/blob/4d1932fcdd1974c820ea60b3286984ebb0c3beaa/src/pip/_internal/utils/urls.py#L31
       71│     """
    →  72│     if not url.startswith("file:"):
       73│         raise ValueError(f"{url} is not a valid file URI")
       74│
       75│     _, netloc, path, _, _ = urlsplit(url)
       76│
 

Start with poetry/console/commands/add.py and poetry/console/commands/init.py, following the requirement parsing path shown in the traceback into poetry/utils/dependency_specification.py and poetry/core/packages/utils/utils.py. Reproduce both poetry add my-wheel.whl and poetry add ./my-wheel.whl; done means the bare wheel filename is accepted without the AttributeError.