vcs: do not change file status on trivial document modifications

platform/platform-impl/src/com/intellij/openapi/vcs/impl/FileStatusManagerImpl.java

@@ -113,6 +113,7 @@ public class FileStatusManagerImpl extends FileStatusManager implements ProjectC
         DocumentAdapter documentListener = new DocumentAdapter() {
           @Override
           public void documentChanged(DocumentEvent event) {
+            if (event.getOldLength() == 0 && event.getNewLength() == 0) return;
             VirtualFile file = FileDocumentManager.getInstance().getFile(event.getDocument());
             if (file != null) {
               refreshFileStatusFromDocument(file, event.getDocument());