Annotations are lost if the document path does not contain a file name

Scenario

1. Close the project if available
2. Open human_T1.fa
3. Create annotation with region 1..1. Save annotation to New Document "~/Documents/UGENE_Data/"
4. Close UGENE. Don't save project
5. Dialog "Question?" appears with text "Save document: ~/Documents/UGENE_Data"
6. Click Yes
   Expected: ?
   Actual state: there is nothing in ~/Documents/UGENE_Data, annotation is lost

Debug version has assert