packaging 24.1: Demonstrate that SpecifierSet.contains excludes semantically matching pre-releases by default.

The `search_known_solution` tool did not return any exact matches for verifying if `SpecifierSet.contains()` includes pre-releases by default. (The closest hit was about upper major boundaries in wildcard less-than requirements, which is a different issue).

This sample pins `packaging` at version `24.1`.

The trap:
A competent model writing a dependency resolver or version checker might logically expect that since `Version('2.1a1') > Version('2.0')` is `True`, then `SpecifierSet('>=2.0').contains('2.1a1')` must also be `True`. 

However, under PEP 440, pre-releases are silently excluded from ranges unless the specifier explicitly mentions a pre-release or the caller explicitly opts in. Thus, `contains('2.1a1')` returns `False` despite the version being mathematically greater than `2.0`. A caller must explicitly pass `prereleases=True` to allow it to be included. This is a common source of bugs when handling beta or alpha user environments.

from packaging.specifiers import SpecifierSet
from packaging.version import Version

def main():
    spec = SpecifierSet(">=2.0")
    prerelease = "2.1a1"
    
    # Prove the version is mathematically greater
    assert Version(prerelease) > Version("2.0"), "2.1a1 is greater than 2.0"
    
    # The trap: > evaluates to True, but contains() returns False
    assert spec.contains(prerelease) is False, "SpecifierSet('>=2.0').contains('2.1a1') returns False rather than True, because pre-releases are silently excluded from version ranges by default under PEP 440."
    
    # Prove the opt-in behavior works
    assert spec.contains(prerelease, prereleases=True) is True, "Must explicitly pass prereleases=True to include it"

if __name__ == "__main__":
    main()

{"case":{"believed":"a pre-release like 2.1a1 is contained in the range \u003e=2.0 because it evaluates as strictly greater than 2.0","caseId":"case:sha256:f9a4d36e6c9cf9b0745784c663b5f846717e7049c97a9faa35ccace80c439442","contract":["SpecifierSet('\u003e=2.0').contains('2.1a1') returns False rather than True, because pre-releases are silently excluded from version ranges by default under PEP 440.","assert Version('2.1a1') \u003e Version('2.0')","assert not SpecifierSet('\u003e=2.0').contains('2.1a1')","assert SpecifierSet('\u003e=2.0').contains('2.1a1', prereleases=True)"],"goal":"Demonstrate that SpecifierSet.contains excludes semantically matching pre-releases by default.","kind":"HOW","packages":["pkg:pypi/packaging@24.1"],"schemaVersion":1,"symbols":["packaging.specifiers.SpecifierSet.contains","packaging.version.Version"]},"contractCommand":["python","contract.py"],"environment":{"arch":"x64","ecosystem":"pypi","executionContext":"python","language":"python","os":"linux","packageManager":"pip","runtime":"python","schemaVersion":1},"license":"MIT-0","packages":["pkg:pypi/packaging@24.1"],"schemaVersion":1,"symbols":["packaging.specifiers.SpecifierSet.contains","packaging.version.Version"],"verifierAdapter":"python@1"}

packaging==24.1