Output of esc_url doesn't allow brackets

[rabmalin]

$args = array(
 'autofocus[control]' => 'blogname',
);
$url = add_query_arg( $args, admin_url('customize.php' ));
echo esc_url($url);

Current output:
http://staging.dev/wp-admin/customize.php?autofocuscontrol=blogname

Expected output:
http://staging.dev/wp-admin/customize.php?autofocus[control]=blogname

I was trying to generate auto focus URL for customize page. I generally use esc_url to escape any URL in WordPress. But I could not produce expected URL when URL is escaped with the function. Is this expected feature of the function? Can someone please help make me clear about this?
Thanks.

[valendesigns]

Here is a patch with unit tests to fix the issue; all other formatting unit tests continue passing. It appears the regex pattern was introduced in #12309 and hasn't changed since.

[dd32]

Duplicate of #16859.