Allow some mutually exclusive same name deps

[BeRT2me]

Given a pyproject.toml that contains:

[[tool.poetry.source]]
name = "torch"
url = "https://download.pytorch.org/whl/cpu/"
priority = "explicit"

[tool.poetry.dependencies]
python = "~3.10"
torch = [
     {version = "^2.0.1", platform = "darwin", source = "PyPI"},
     {version = "^2.0.1+cpu", platform = "linux", source = "torch"}
]

Running poetry export produces:

torch==2.0.1+cpu ; python_version >= "3.10" and python_version < "3.11" and (sys_platform == "darwin" or sys_platform == "linux")

Which is strictly wrong. Attempting to install this on a darwin system will fail.

By stripping the package version of the "local" portion (+cpu), then due to how they're ordered by default in the poetry.lock file, both dependencies are able to be correctly included.

With this change, poetry export correctly produces:

torch==2.0.1 ; python_version >= "3.10" and python_version < "3.11" and sys_platform == "darwin"
torch==2.0.1+cpu ; python_version >= "3.10" and python_version < "3.11" and sys_platform == "linux"

---

P.S.
I also think things look better with the built-in textwrap.dedent to keep relevant text in-line rather than to the left.

MARKER_PY27_PY36_ONLY was added due to line-length issues.

[BeRT2me]

See https://stackoverflow.com/questions/77141598/poetry-config-for-torch-installation

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[radoering]

That does not feel like a valid fix. I think it is not sufficient to group packages by name. Probably, they should be grouped by name and source. Then, the correct locked package can be chosen no matter what's the order in the lockfile.

[BeRT2me]

Ye, I'm going to rethink this if I have time.