sum the boot-wait budgets of units that start one after another in a container, and check it

nix/container-modules/swarm-container.nix

@@ -15,7 +15,9 @@
 # `systemctl start --no-block` (./swarm-journal-forwarder.nix is the pattern).
 # `module-eval-swarm-services-switch` fails on a unit whose budget, stated or the
 # manager's 90 s default, reaches the limit, unless the unit is listed there with
-# a reason.
+# a reason. It also adds the budgets of units ordered one after another by
+# `after`/`before`, and fails when the longest such chain reaches the limit (a
+# unit listed there adds 0 s) or the ordering has a cycle.
 { config, lib, ... }:
 let
   cfg = config.services.hyperhive.swarmContainer;