Fix test_directory_map

See #2475 and point 2 of #2334
Fix an argument in test_directory_helper
[ci skip] Skip directory_map() test when opendir() fails to open a VFS dir
[ci skip] Simplify get_file_info()
Merge pull request #2538 from vlakoff/develop-4

Fix config_item() returning stale values
[ci skip] Add a changelog entry