Superfluous ampersand in MCP action dropdown URL (results in "...?&f=..." rather than "...?f=...")

Summary:
The dropdown action jumplist at the bottom of the MCP page specifies a form submit URL that always contains a superfluous ampersand (&). Ie: The form submission URL ends up being: "mcp.php?&f=" rather than just ...?f=...

Steps to recreate:
1) Go to: http://<boardURL>/viewtopic.php?f=&t=
2) Click the moderator control panel link
3) Tick any post
4) Choose any action in the dropdown box at the bottom of the page - eg: delete post.
5) Press submit
6) Note subsequent page URL

Expected results:

• Subsequent page URL is in the format: "mcp.php?f="...

Actual results:

• Subsequent page URL is in the format: "mcp.php?&f="... (ie: with a superfluous ampersand)

Reproducibility:

• Every time.

Additional Info:
I've looked through the phpBB 3.0.7-PL1 source, and believe the error lies in "mcp.php", on line 330, in function extra_url().

The function uses lines such as:

$url_extra .= ($forum_id) ? "&f=$forum_id" : '';

Whereas it should presumably be:

$url_extra .= ($forum_id) ? "f=$forum_id" : '';

...etc

In fact, I found superfluous ampersands in two other parts of the mcp file as well, eg: function _module_warn_url and also function _module_notes_url.

Thanks!