coverage source= skips unimported files in dirs without __init__.py

coverage.py 7.17.0 (pytest-cov 7.1.0): with a source set (--cov=pkg, --cov=., or [tool.coverage.run] source), files that were never imported are reported at 0% only if coverage can find them. It always scans the named source directory itself, but walks into subdirectories only when they contain an __init__.py. With implicit namespace packages, --cov=. silently drops pkg/b.py and --cov=pkg drops pkg/sub/c.py, so the total can read 100% while whole modules have no tests. Fix: pass every leaf directory (--cov=pkg --cov=pkg/sub, tested), or compare the report's file list with git ls-files '*.py'.