Index: openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl,v
diff -u -N -r1.3.2.11 -r1.3.2.12
--- openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	30 Jan 2017 16:14:10 -0000	1.3.2.11
+++ openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	31 Jan 2017 12:58:29 -0000	1.3.2.12
@@ -593,9 +593,12 @@
     # If required from headers, force a multipart form
     set req_content_type [ns_set iget $headers "content-type"]
     if {$req_content_type ne ""} {
-        set multipart_p [string match -nocase "*multipart/form-data*" $req_content_type]
-        # avoid duplicated headers
-        ns_set idelkey $headers "Content-type"
+        if {[set multipart_p [string match -nocase "*multipart/form-data*" $req_content_type]} {
+            # content-type was set as multipart by hand, we delete the
+            # manual header, because we will create a proper one, with
+            # boundaries etc later
+            ns_set idelkey $headers "Content-type"
+        }
     }
     
     ## Construction of the payload