[bug] Conan does not install correct dependencies on OSX when using poetry

[StefanUlbrich]

Environment Details (include every applicable attribute)

• Operating System+version: OSX Catalina
• Compiler+version:
• Conan version: 1.24.0
• Python version: 3.7

Steps to reproduce (Include if Applicable)

poetry add conan -D
conan --version

Related to Poetry issue 2269.
The tar ball on pypa does not contain the correct meta data (only for the platform it has been build with). It is recommended to use markers (see PEP 508) to express conditional requirements.

Logs (Executed commands with output) (Include/Attach if Applicable)

poetry run conan --help
Traceback (most recent call last):
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/bin/conan", line 6, in
from pkg_resources import load_entry_point
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 3191, in
@_call_aside
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 3175, in _call_aside
f(*args, **kwargs)
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 3204, in _initialize_master_working_set
working_set = WorkingSet._build_master()
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 583, in _build_master
ws.require(requires)
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 900, in require
needed = self.resolve(parse_requirements(requirements))
File "/Users/stef/Library/Caches/pypoetry/virtualenvs/temp-31h-1b3r-py3.7/lib/python3.7/site-packages/pkg_resources/init.py", line 786, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pyOpenSSL<19.0.0,>=16.0.0' distribution was not found and is required by conan