Description:
------------
parse_url gets lost when providing an url with no scheme in front, this goes totally against the RFC which allows urls with no scheme

Test script:
---------------
php > echo var_dump(parse_url("//search.yahoo.com/search?p=car"));

array(2) {
  ["path"]=>
  string(25) "//search.yahoo.com/search"
  ["query"]=>
  string(5) "p=car"
}

php > echo var_dump(parse_url("http://search.yahoo.com/search?p=car"));

array(4) {
  ["scheme"]=>
  string(4) "http"
  ["host"]=>
  string(16) "search.yahoo.com"
  ["path"]=>
  string(7) "/search"
  ["query"]=>
  string(5) "p=car"
}

Expected result:
----------------
php > echo var_dump(parse_url("//search.yahoo.com/search?p=car"));

array(2) {
  ["host"]=>
  string(16) "search.yahoo.com"
  ["path"]=>
  string(7) "/search"
  ["query"]=>
  string(5) "p=car"
}