The per-recipe sysroot and stage cache used mtime of the dep pkgar
files to detect when a rebuild was needed. Any mtime bump on relibc
or any leaf dep (including the pre-cook relibc in build-redbear.sh)
would cascade-rebuild every downstream per-recipe sysroot even when
the dep's content was bit-identical. The resulting transient sysroot
extractions produced 'C compiler cannot create executables' and
'configure error' failures that retried fine standalone.
Replace the mtime checks with a blake3 content-hash fingerprint of
the dep pkgar set:
- For the per-recipe sysroot: store the fingerprint in
<target>/sysroot/.tags/deps-fingerprint and rebuild only when the
computed fingerprint does not match.
- For the per-recipe stage: store two fingerprints at
<target>/.deps-fingerprint and <target>/.host-deps-fingerprint.
Rebuild stage only when (source changed) OR (deps content changed)
OR (host-deps content changed) OR (auto_deps.toml missing).
This eliminates the transient build failures in 'make live' / 'build-redbear.sh'
and aligns the cache invalidation signal with the actual content the
recipe depends on, not the arbitrary mtime of the dependency package.
vasilito
68c795f4d3