Recognize GNU GPL v2 release notices - #5426

Fixes #4942

Short GNU GPL v2 release notices match unrelated partial composite rules instead of an exact GPL v2 notice.

Add two exact GPL v2 notice rules and cover both license/licence spellings with full-coverage hash-match regressions.

Validation on Python 3.12, with a fresh license index:

• python -m pytest -q tests/licensedcode/test_match_hash.py tests/licensedcode/test_license_models.py — 53 passed.
• The new regression fails on unchanged develop.

CI baseline comparison

The Python 3.14 license_validate_ignorables_2 job fails two assertions for missing ignorable URLs in fsl-1.1_1.RULE and fsl-1.1_2.RULE. Both assertions fail with the same output on upstream commit e423b48a1fdbff26219fbeafe7e9bdef293b91fc. The PR has 31 passing checks. Azure reports the failed job and its parent pipeline separately.

Upstream build · PR build

Tasks

• Reviewed the contribution guidelines.
• Descriptively titled PR linked to the original issue.
• Upstream CI passes (pending after submission; relevant local results are listed above).
• Uniquely named feature branch with no merge conflicts against the checked upstream base.
• Updated CHANGELOG.rst and AUTHORS.rst.
• Documentation: no user-facing documentation change needed for this fix.

AI assistance: Codex assisted with investigation, implementation and local tests.