Poetry do not install package version with a post suffix, even in exact requirements

[7sDream]

• I am on the latest Poetry version.

• I have searched the issues of this repo and believe that this is not a duplicate.

• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: macOS 11.1

• Poetry version: 1.1.4

• Link of a Gist with the contents of your pyproject.toml file: N/A, a empty project is enough to reproduce this issue

Issue

Try use this command to install nonebot2 package, version 2.0.0a9.post1(comply with PEP440), which is exist in pypi:

poetry add nonebot2@2.0.0a9.post1 --allow-prereleases

but get version 2.0.0.a9 installed:

And pyproject.toml says version is 2.0.0a9.post1:

[tool.poetry]
name = "poetrytest"
version = "0.1.0"
description = ""
authors = ["7sDream <i@7sdre.am>"]

[tool.poetry.dependencies]
python = "^3.9"
nonebot2 = {version = "2.0.0a9.post1", allow-prereleases = true}

[tool.poetry.dev-dependencies]

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

I can use pip to install/upgrade it to target version, though:

Any ideas?

[finswimmer]

Hello @7sDream,

thanks for reporting. The problem here is not the .post release per-se. The problem is, that it is a post release of a prerelease, which poetry currently doesn't handle correct.

fin swimmer

[radoering]

Should be fixed via python-poetry/poetry-core#327.

[dimbleby]

confirmed that with latest master code from poetry and poetry-core indeed version 2.0.0a9.post1 is installed, this can be closed

[github-actions]

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