Sounds reasonable.

Why P1, is this hitting something urgently?

chingcodes@ this is probably not too complex, want to take a crack in your spare time?

P1 b/c this feature is desired, so I figured "for current milestone" wasn't unreasonable. Feel free to downgrade if you disagree.

We aren't very milestone oriented on cros infra. I'll call this a P2.

It's harder than it sounds, because you have to run without a config until post-bootstrap. We use the build config to select the builder class, and the sync stage. Both of which are needed for all pre-bootstrap work.

Hum... we can have pre-bootstrap logic that checks out chromite to the branch then invokes cbuildbot. 

For cleanliness, I'd create a new script for this, instead of making cbuildbot's startup even more complicated.

Using this pre-bootstrap bootstrap would let us simplify the buildbot recipes to always pull chromite at TOT.

Bonus Goal (very secondary):
If it could apply chromite CLs, that would let us trybot test CLs that are creating new configs.

Downgrading P2s that haven't been modified in more than 6 months, which have no component or owner.