publish: no-op when joining our own notebook
publish: no-op when joining our own notebook

Fixes #3300.

urbit/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,ngzax/urbit,urbit/urbit,urbit/urbit,ngzax/urbit,urbit/urbit