Name the error of a fetch whose lock waits for an unpublished package (issue 1587, ADR 0500 §6)

waits for: is the prefix the builder turns into a queued key with Waits; it is not
one of the errors held until the fingerprint changes.

go/delivery/builder_reference_test.go

@@ -133,3 +133,11 @@ func TestADoneKeyWithNoArtifactIsReferenced(t *testing.T) {
 		t.Fatalf("Referenced = %v, %v; want true", ok, missing)
 	}
 }
+
+// A Node fetch that finds the lock naming a package version the registry does not hold fails with WaitsFor; the
+// builder then writes the key queued with Waits, and the error is not one that waits for the fingerprint to change.
+func TestWaitsForIsAPrefixThatIsBuiltAgain(t *testing.T) {
+	if WaitsFor != "waits for: " || FailedUntilChanged(WaitsFor+"@novox/mesh-sdk@0.1.15") {
+		t.Fatalf("WaitsFor = %q", WaitsFor)
+	}
+}