如何使用WebRequest凭据访问vb .net中的GitHub的私有存储库.diff

Question

我想访问GitHub私有存储库的.diff文件。我有以下代码，但不起作用。

Dim myReq As HttpWebRequest = WebRequest.Create(url)
Dim netCred As NetworkCredential = New NetworkCredential("usr", "pass")
Dim credentials As ICredentials = netCred.GetCredential(url, "Basic")
myReq.Credentials = credentials
myReq.PreAuthenticate = True
Try
    Dim response As HttpWebResponse = CType(myReq.GetResponse(), HttpWebResponse)
Catch ex As System.Net.WebException
    MessageBox.Show(ex.Message)
End Try

有什么不对吗？ WebException包含的消息是＆＃34;远程服务器中的错误。 （404）未找到＆＃34;