file.mimetypes needs entry for m4v

This directly matches the information at http://en.wikipedia.org/wiki/M4V.

RTBC pending testbot review

I just stumbled upon this issue while reviewing some of the great work being done on the media module; it looks like the version was set to 7.x-dev by mistake?
I'm moving this to 8.x and changing the status to needs review. I'll change it back to RTBC after the testbot runs.

I conditionally apologize if I'm wrong about this!

mimetype.patch queued for re-testing.

Confirming this is ready against both 8.x and 7.x.

Committed to 8.x, moving to 7.x for webchick to look at.

Committed and pushed to 7.x. Thanks!

Though one question. Is it possible a contributed module has already used ID 348 for something else..?

They should be adding their entries properly. If not, then it's a bug in that module:

/**
 * Implements hook_file_mimetype_mapping_alter().
 */
function file_entity_file_mimetype_mapping_alter(&$mapping) {
  // Fix the mime type mapping for ogg.
  // @todo Remove when http://drupal.org/node/1239376 is fixed in core.
  $new_mappings['ogg'] = 'audio/ogg';

  // Add support for m4v.
  // @todo Remove when http://drupal.org/node/1290486 is fixed in core.
  $new_mappings['m4v'] = 'video/x-m4v';

  // Add support for mka and mkv.
  // @todo Remove when http://drupal.org/node/1293140 is fixed in core.
  $new_mappings['mka'] = 'audio/x-matroska';
  $new_mappings['mkv'] = 'video/x-matroska';

  foreach ($new_mappings as $extension => $mime_type) {
    if (!in_array($mime_type, $mapping['mimetypes'])) {
      // If the mime type does not already exist, add it.
      $mapping['mimetypes'][] = $mime_type;
    }

    // Get the index of the mime type and assign the extension to that key.
    $index = array_search($mime_type, $mapping['mimetypes']);
    $mapping['extensions'][$extension] = $index;
  }
}

Right, I understand that. But $mapping['mimetypes'][] = $mime_type; in an array $mapping['mimetypes'] with 348 items already in it would give you an ID of 348... no? Or does it not matter, since the code always refers to $mapping['extensions'][$extension] instead?

No, the id of $mime_type in this case would be 349. The key is using it properly.