Fix

Avoid sending spurious changedMetadata updates during sync

Closes #743

rojo-test/serve-tests/changed_metadata/default.project.json

@@ -0,0 +1,18 @@
+{
+  "name": "changed_metadata",
+  "tree": {
+    "$className": "DataModel",
+    "Workspace": {
+      "$className": "Workspace",
+      "Baseplate": {
+        "$className": "Part",
+        "$properties": {
+          "Anchored": true
+        }
+      },
+      "Thing": {
+        "$path": "a"
+      }
+    }
+  }
+}