Media internet fails to validate file type when multiple files type have the same mime

Reproduce:

1. Add a new file type with mime type image/*.
2. Edit field instance settings to allow only the Image file type and excluding the newly created file type.
3. Use media internet to add a file that fits the two file types mime rules.
4. An error occurs "Only the following types of files are allowed to be uploaded: image, etc ..."

Problem:

media_file_validate_types() uses file_get_type() function form file_entity.file_api.inc which will returns the value of the first file type match, regardless if the type is allowed or not for the field.

function file_get_type($file) {
  $types = module_invoke_all('file_type', $file);
  drupal_alter('file_type', $types, $file);

  return empty($types) ? NULL : reset($types);
}

Proposed solution

Replace file_get_type() in media_file_validate_types() by file_entity_get_filetype_candidates() to validate the file against all allowed file types for the field instance.

Related issues

• Using file_entity_get_filetype_candidates() will trigger an error in file_entity_access() "Undefined property: stdClass::$fid" since the file is not uploaded yet and does not have a fid.
  Reference issue #2312603: Undefined property: stdClass::$fid in file_entity_access() .