This build:

https://uberchromegw.corp.google.com/i/chromeos/builders/master-paladin/builds/19597

was testing a manifest change with a broken branch reference:

crrev.com/c/1192229

Leading to repeated errors:

> Failing (and retrying) repeatedly with "[W git.go:283] Transient error string identified in STDERR: "fatal: Couldn't find remote ref refs/head/cups-2-2-8\n"

I killed this build early, but the stage had already been retrying for ~an hour.