- _read_etag collapses into a single try/except that handles both stat
and read failures (and the unlink) uniformly.
- _mtime_seconds() helper compares mtimes at whole-second resolution
instead of nanoseconds. Sub-second precision varies by filesystem
(FAT does 2s, NTFS 100ns, APFS/ext4 ns); whole seconds is the only
resolution every supported filesystem can preserve through a
set+read round-trip.
- has_remote_file_changed: walrus-assign `etag` and `new_etag` instead
of an explicit binding + immediate check.
- New test fixtures `mock_requests_head`, `mock_requests_get`,
`mock_has_remote_file_changed`, `mock_write_file` replace the
per-test `@patch(...)` decorator stacks. Tests are simpler and the
fixtures can be reused by future tests in the file.
J. Nick Koston
b78bca0dc7