The author exploited this by adding a space to the URL so it no longer started with http:// rather (space)http:// but it looks like the call to Replace would be ineffective if the URL started with HTTP:// as well.
bool flag2 = file.Location.ToLower().StartsWith("http://");
if (flag2)
{
file.Location = file.Location.Replace("http://", "https://");
}