• 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: OSX

• Poetry version: 0.12.11

• Link of a Gist with the contents of your pyproject.toml file: https://gist.github.com/lvkswrks/9967aeedc34f967efeda9c9d429efb5f

Issue

Poetry seems to have problems parsing requirement markers as illustrated below

setup(
    # ...
    install_requires = [
        'pyarrow==0.9.0;platform_system!="darwin"',
        'pyarrow==0.9.post1;platform_system=="darwin"',
    ],
)

It will fall into an infinite recursion and crash at some point with

0: Duplicate dependencies for pyarrow
0: Different requirements found for pyarrow (0.9.0) and pyarrow (0.9.post1).
1: Version solving took 0.056 seconds.
1: Tried 1 solutions.
0: Retrying dependency resolution for Python (>=3.6,<4.0).
1: fact: test-multiline is 0.1.0
1: derived: test-multiline
1: fact: test-multiline depends on py-setup (*)

Please also see a minimal example project configuration I uploaded to Gist.