The newly added cg-admin-rewritehist script is broken in cogito-0.17.1-1.fc5, the cogito author has been informed, and approximately 30 s after I reported it to him it was fixed, so the next version should work :-)
Thanks for the report. If I can get a fix from Petr I'll issue a cogito-0.17.1-2 update. Otherwise I'll pick it up with next upstream release.
As for me, I'm perfectly fine waiting for the upstream release, so no need to push out a patched rpm because of me. Rewriting history probably isn't that common after all.
Heh, already cherry picked and pushed out a release ;-) Should show up in today's Fedora Extras builds.