The drain-gate abort message told the operator a rerun "with or without
--no-build" would finish the restart. That is wrong: by the time this
message can fire, stage_built_jar has already moved the jar off $JAR, so
--no-build hits require_no_build_jar's own refusal. Reworded to say the
rerun must NOT use --no-build, and why: the built jar is no longer at the
live path that --no-build requires.
Also added a test pinning jar_id()'s no-argument default (reports $JAR,
the live path) and its explicit-argument behavior (reports that path
instead), per fleetd #511 item 2. Not adding a test for the JAR_STAGED rm
-f at line 578 (fleetd #511 documents it as an equivalent mutant — mvn
clean install deletes target/ on the next line regardless).
Dai Ha