d618aed6

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Tune NixCI: hand-specify dependencies, disable auto-discovery

Automatic dependency discovery walks the derivation closures to infer ordering;
on a no-op rebuild (every job already cached) that analysis is the only cost.
Specify the graph by hand and turn discovery off so a no-op is as fast as
possible, while still building the shared deps derivation before its consumers.