When using the multipart/form-data, libsoup insert the header "Content-Transfer-Encoding".

This causes problems with some servers I try to upload files to.

According to RFC 2616 
Section 3.6 Transfer Codings
<cite>
   Transfer-codings are analogous to the Content-Transfer-Encoding
   values of MIME [7], which were designed to enable safe transport of
   binary data over a 7-bit transport service. However, safe transport
   has a different focus for an 8bit-clean transfer protocol. In HTTP,
   the only unsafe characteristic of message-bodies is the difficulty in
   determining the exact body length (section 7.2.2), or the desire to
   encrypt data over a shared transport.
</cite>
and 
Section 19.4.5 No Content-Transfer-Encoding
<cite>
   HTTP does not use the Content-Transfer-Encoding (CTE) field of RFC
   2045. Proxies and gateways from MIME-compliant protocols to HTTP MUST
   remove any non-identity CTE ("quoted-printable" or "base64") encoding
   prior to delivering the response message to an HTTP client.

   Proxies and gateways from HTTP to MIME-compliant protocols are
   responsible for ensuring that the message is in the correct format
   and encoding for safe transport on that protocol, where "safe
   transport" is defined by the limitations of the protocol being used.
   Such a proxy or gateway SHOULD label the data with an appropriate
   Content-Transfer-Encoding if doing so will improve the likelihood of
   safe transport over the destination protocol.
</cite>

I believe it is incorrect to use the header "Content-Transfer-Encoding" within HTTP.
This can be supported by the fact that Mozilla Firefox do *not* insert "Content-Transfer-Encoding" in multipart when uploading files ascii-text, non-ascii-text nor binary data. 

This is easily fixed in soup-multipart.c in function soup_multipart_append_form_file () by removing the following lines:

	if (content_type && strncmp (content_type, "text/", 5) != 0) {
		soup_message_headers_append (headers,
					     "Content-Transfer-Encoding",
					     "binary");
	} else {
		soup_message_headers_append (headers,
					     "Content-Transfer-Encoding",
					     "8bit");
	}