The GitHub-generated archives Source Code (zip) and Source Code (tar.gz) are incomplete (read more at #156 (comment)). Instead, use v6.5.2.tar.gz. Its SHA256 should be d95514604e5466a047ecce504459aa418997a6a24af99455294a9181b1833d98. Or clone this repo at the tag v6.5.2 (and run git archive if you need an archive).