portsnap: metadata is corrupt

[cali clarke]

Last one from me today, I hope.

# rm -r /var/db/portsnap /usr/ports && mkdir /var/db/portsnap /usr/ports
# portsnap fetch extract
<59mb download>
Could not open <sha256 string>: no such file or directory
metadata is corrupt

I've tried all of the portsnap mirrors and have downloaded the same thing
about ten times now.

8.0-RELEASE amd64.

I've seen various reports of this problem around the web but no solutions.