mounts: clear a failed mount of its own whose source was away, and the failure of a unit it takes over, so neither is said as the machine's own failed unit (hq ADR 0263 rules 4 and 6)

modules/mounts/cmd/mounts/write_test.go

@@ -77,6 +77,11 @@ func (f *fakeSystem) run(_ context.Context, name string, args ...string) (string
 	case "enable":
 		u := args[len(args)-1]
 		f.units[u] = map[string]string{"ActiveState": "active", "UnitFileState": "enabled"}
+	case "reset-failed":
+		u := args[len(args)-1]
+		if f.units[u]["ActiveState"] == "failed" {
+			f.units[u]["ActiveState"], f.units[u]["Result"] = "inactive", "success"
+		}
 	}
 	return "", nil
 }