First couple of print statements for debugging a Heisenbug
More debugging
And even more debugging
Also reset "otherRequestInProgress" if the request fails
Stop customized RequestHandler from sending another set of headers after the response

This was causing the GET request for the list of files following directly after a successful response from an upload to get associated with the second empty response sent directly after the upload and such lead to a funny timing issue causing the file list not to update correctly since the response to THAT request -- while received by the client -- could then not be processed.

See #455