Using --autoresolve with -P and packages with version ranges fails confusingly

[PeterJCLaw]

It seems that passing a package range to -P when also using --autoresolve and more than one layer of requirements causes pip-compile-multi to get confused about where some of the version pins are coming from.

This is reproducible with:

requirements/prod.in:

markupsafe

requirements/prod.txt:

# SHA1:2f781f20c9698050fd9afac72c0364db5deacb05
#
# This file is autogenerated by pip-compile-multi
# To update, run:
#
#    pip-compile-multi
#
markupsafe==2.0.1
    # via
    #   -c requirements/tests.txt
    #   -r requirements/prod.in

requirements/tests.in:

-r prod.in

requirements/tests.txt:

# SHA1:939d3916ae2e78296c77d899249472d04707c772
#
# This file is autogenerated by pip-compile-multi
# To update, run:
#
#    pip-compile-multi
#
-r prod.txt

then:

$ pip-compile-multi --autoresolve -P 'markupsafe<2.1.2'
Creating a temporary file with all dependencies at requirements/tests.txt
Locking requirements/prod.in to requirements/prod.txt. References: []
Locking requirements/tests.in to requirements/tests.txt. References: ['requirements/prod.in']
Package markupsafe was resolved to different versions in different environments: 2.1.1 and 2.0.1
Traceback (most recent call last):
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/cli_v1.py", line 26, in cli
    recompile()
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/actions.py", line 31, in recompile
    compile_topologically(env_confs, deduplicator)
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/actions.py", line 38, in compile_topologically
    if env.maybe_create_lockfile():
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/environment.py", line 51, in maybe_create_lockfile
    self.create_lockfile()
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/environment.py", line 72, in create_lockfile
    self.fix_lockfile()
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/environment.py", line 134, in fix_lockfile
    sections = [
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/environment.py", line 135, in <listcomp>
    self.fix_pin(section)
  File "/tmp/venv/lib/python3.10/site-packages/pipcompilemulti/environment.py", line 211, in fix_pin
    raise RuntimeError(
RuntimeError: Please add constraints for the package version listed above