CubeComming #804: since 2.6.7, importing already-tagged files (Bruno Mars,
Coldplay) blanked EVERY tag and filed them under "Unknown Artist". Root cause:
both metadata-enhancement blocks in post_process_matched_download did
`except Exception: wipe_source_tags(file_path)` — a full audio.tags.clear() +
strip + clear_pictures. But enhancement throwing means NO new tags were
written, so wiping just destroys the originals. A transient enhancement error
on a well-tagged file = total metadata loss. (The reported "bitrate change" is
a red herring: mutagen padding on re-save, not a re-encode — ReplayGain only
reads via ffmpeg and tags via mutagen.)
Fix: gate the failure-path wipe on should_wipe_tags_on_enhancement_failure()
(new pure, tested policy) — only wipe UNMATCHED downloads (likely junk source
tags); NEVER wipe a clean/matched import, preserve its existing tags + log.
Unmatched-download behavior is unchanged, so the only thing that changes is the
broken case.
Tests: 3 pin the policy (clean→preserve, unmatched→strip, falsey→strip).
1211 import/pipeline/metadata tests pass.
d9dcf57f43