"The Trac Environment needs to be upgraded" after installing locally

[Tim Graham]

After following the install instructions on a local machine, you'll get "The Trac Environment needs to be upgraded. " because SELECT value FROM system WHERE name='database_version'
returns no values because the system table is empty. I'm not sure how
that table is populated during a normal Trac install. Possibly as part
of https://trac.edgewall.org/wiki/TracInstall#CreatingaProjectEnvironment.

My investigation is incomplete but I wanted to document this for anyone else who runs into this.