Changes to conf.py don't trigger a rebuild

[ojacobson]

STR:

1. Start phix and wait for it to build your docs once.
2. Edit conf.py and save your changes.
3. Watch the phix logs.

Expected: phix rebuilds the documentation with the new Sphinx configuration.

Actual: phix does not rebuild the documentation, and the configuration changes are not applied until the next action that triggers a rebuild.

[wlonk]

Resolved in fe4f3b.