On Windows, when using a filesystem that is located on the network, the path doesn't begin with a drive (like in C:\some\path) but with \\ (like in \\SOMEHOST\some\path)

This can cause the following error crash during the dependency container generation:

InvalidArgumentException: [WARNING 1549] failed to load external entity "file:////HOST/WWW/perso/username/sf/vendor/symfony/symfony/src/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd" (in n/a - line 0, column 0)

For instance, in Component/DependencyInjection/Loader/XmlFileLoader.php, replacing the following:

$drive = '\\' === DIRECTORY_SEPARATOR ? array_shift($parts).'/' : '';
$location = 'file:///'.$drive.implode('/', array_map('rawurlencode', $parts));

With:

if (0 !== stripos($location, '//')) {
  $drive = '\\' === DIRECTORY_SEPARATOR ? array_shift($parts).'/' : '';
  $location = 'file:///'.$drive.implode('/', array_map('rawurlencode', $parts));
}

Fixes this issue.
I can make a PR, but I'm not sure this is the good solution.