_stream.py: workspace_close deletes the stored project reference

buildstream/_stream.py

@@ -536,6 +536,10 @@ class Stream():
                 except OSError as e:
                     raise StreamError("Could not remove  '{}': {}"
                                       .format(workspace.get_absolute_path(), e)) from e
+        else:
+            # TODO: At some point, closing a workspace only deletes the file if no projects are using it.
+            workspace_local = workspaces.create_workspace_local(workspace.get_absolute_path())
+            workspace_local.delete()
 
         # Delete the workspace and save the configuration
         workspaces.delete_workspace(element_name)