Fixed crash bug during indexing
Fixed crash bug during indexing

(cherry picked from commit c8aac4cde6e22677484999e3d901b820da271f6d)

uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend