title: Using updateEntry() method with dotnetzip won't overwrite files correctly
body: <p>I've been having a bit of a problem lately. I've been trying to extract one zip file into a memory stream and then from that stream, use the <code>updateEntry()</code> method to add it to the destination zip file.</p>
  
  <p>The problem is, when the file in the stream is being put into the destination zip, it works if the file is not already in the zip. If there is a file with the same name, it does not overwrite correctly. It says on the dotnetzip docs that this method will overwrite files that are present in the zip with the same name but it does not seem to work. It will write correctly but when I go to check the zip, the files that are supposed to be overwritten have a compressed byte size of 0 meaning something went wrong. </p>
  
  <p>I'm attaching my code below to show you what I'm doing:</p>
  
  <pre><code>ZipFile zipnew = new ZipFile(forgeFile);
  ZipFile zipold = new ZipFile(zFile);
  
  using(zipnew) {
      foreach(ZipEntry zenew in zipnew) {
          percent = (current / zipnew.Count) * 100;
          string flna = zenew.FileName;
          var fstream = new MemoryStream();
  
          zenew.Extract(fstream);
          fstream.Seek(0, SeekOrigin.Begin);
  
          using(zipold) {
              var zn = zipold.UpdateEntry(flna, fstream);
              zipold.Save();
              fstream.Dispose();
          }
          current++;
      }
      zipnew.Dispose();
  }
  </code></pre>