The previous patch_jpegdec.py used in-place string replacement with a
single shared marker for two distinct DC writes (main store and
successive-approximation update). If only one of the two anchors
matched, the file was written half-patched and the shared marker locked
the partial state in for every subsequent run.
Generate the fixes as `git format-patch` artifacts under
scripts/jpegdec_patches/, then apply them in lexical order via
`git apply`. Idempotency is decided by git itself: `--check --reverse`
succeeds means already applied; `--check` succeeds means appliable;
neither aborts the build rather than leaving a half-patched file.
No behaviour change to the patched JPEGDEC source: same redirect, same
DC guards, same intent. Just stops the pre-build script from doing
something it has no business doing.
Jeremy Klein
9e68ced046