Masterpress 1.3.6 is a compatibility release. It resolves an edge case with shared fieldsets not working for MySQL 8 when the fieldset is limited to more than 1 post type or taxonomy or excluding any post types or taxonomies.
WOOF_File :: exists()
Checks if this file object does indeed point to a valid file path. This could happen if a file was manually deleted from a file system, but was still present as the value of a custom field, for example.