disk_bytes() summed the clone tree with rglob + stat() as a size cap
before every git command. On a blob:none clone, `git show` triggers an
on-demand blob fetch that writes and deletes transient
.git/objects/pack/*.rev files, so a path rglob had just listed could be
gone by the stat() call -> FileNotFoundError aborted the whole draft as
an instrument_failure. The race can hit any candidate, so it was a
non-deterministic draft-killer (observed extracting a real npm repo).
Skip a file that raises OSError mid-walk; the size cap is unaffected.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
