Merge pull request #1730 from balena-os/wrong-delta-source

Fix supervisor using wrong source for deltas

src/compose/application-manager.ts

@@ -596,12 +596,15 @@ export function bestDeltaSource(
 				return availableImage.name;
 			}
 		}
-	}
+	} else {
+		// This only makes sense for dependent devices which are still
+		// single app.
 		for (const availableImage of available) {
 			if (availableImage.appId === image.appId) {
 				return availableImage.name;
 			}
 		}
+	}
 	return null;
 }