Guess you're happy with that answer. To fix the mirroring, he needs to create the non-zero sizes (contents don't matter) in the  ARCHIVE/=meta-info/http-blows file.
Then he needs to run archive-fixup on the name of the mirror
So, for example, if he can ssh to where the mirror is, he can echo "yeah" > HERE/IS/MY/MIRROR/=meta-info/http-blows, then back on the machine that has the original source, run archive-fixup ARCHIVE-MIRROR

Thank you interweb, you fixed it.