I detected this bug when trying to use "source-integration" plugin.

Function url_get( $p_url ) in url_api.php file doesn't work properly when 'allow_url_fopen' is set to 'Off'.

I fixed it replacing code:
function url_get( $p_url ) {

# Generic PHP call
if( ini_get( 'allow_url_fopen' ) ) {
    return @file_get_contents( $p_url );
}

to:
function url_get( $p_url ) {

# Generic PHP call
if( ini_get_bool( 'allow_url_fopen' )) {
    return @file_get_contents( $p_url );
}

Possibly the problem ocurs also in other functions