When working on MDL-76309 I realized that file_storage::get_pathname_hash() does not check whether the $pathname parameter has a trailing / leading slash.

As the entries in mdl_files always have a trailing slash in the pathname, get_pathname_hash() should ensure that to find the right files and to avoid collisions. This could happen when using pathinfo() PHP function which only returns the trailing slash in dirname when it's the root directory (in all other cases it is omitted).