add edit key unit test for no-op

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/SaveKeyringParcel.java

@@ -82,6 +82,10 @@ public class SaveKeyringParcel implements Parcelable {
         mRevokeSubKeys = new ArrayList<>();
     }
 
+    public boolean isEmpty() {
+        return isRestrictedOnly() && mChangeSubKeys.isEmpty();
+    }
+
     /** Returns true iff this parcel does not contain any operations which require a passphrase. */
     public boolean isRestrictedOnly() {
         if (mNewUnlock != null || !mAddUserIds.isEmpty() || !mAddUserAttribute.isEmpty()