Error 400 on SERVER: Not authorized to call search on /file_metadata/pluginfacts

I'm using the all-in-one install via staypuft-installer. According
to https://groups.google.com/d/msg/puppet-users/qDIgAvJdeqg/slA5qMsXraAJ
and a comment here:
http://serverfault.com/questions/422487/puppet-permissions-issue-reported-on-client
this is probably due to the puppet master version being older than the
puppet agent.

So, I need to either upgrade my puppet master (currently running 2.7.25),
or downgrade the puppet agent (3.7.1), and I'm trying to figure out which
will be easier.

Issues:

  • I really don't want to mess with the all-in-one install aspect of
    staypuft-installer, as I'll probably need to do significant work to tear it
    apart and put it back together with a different puppet.
  • The staypuft provisioning uses RHEL7 (or CentOS7 in my case), and there's
    no RPM in el7 for puppet 2.7, so I would need to either try installing el6
    version (probably lots of bad dependencies) or install it from the tarball
    (unsure how to do that).

Any ideas? What would be the least work, or at least the greatest
likelihood of actually working?

Note: I had a separate thread about this
here: https://groups.google.com/forum/#!topic/foreman-users/YQRlUgOp75E
But, now I'm thinking it's not a permissions issue, so the thread title is
misleading. But you can check there for full error message.