base/conversion: setContentType() before converting to base format (!1751).

Some conversion (TextDocument) depend on the content type, so it's necessary to
first update the content type before trying to convert to base format.

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/interaction_Document_base_convertable.xml

@@ -10,8 +10,9 @@
             <key> <string>categories</string> </key>
             <value>
               <tuple>
-                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_convertToBaseFormat</string>
+                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_guessMimeType</string>
                 <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_upload</string>
+                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_convertToBaseFormat</string>
               </tuple>
             </value>
         </item>

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/interaction_Document_file.xml

@@ -22,7 +22,7 @@
         </item>
         <item>
             <key> <string>guard_expression</string> </key>
-            <value> <string>here/hasFilename</string> </value>
+            <value> <string>not: here/isSupportBaseDataConversion</string> </value>
         </item>
         <item>
             <key> <string>guard_group</string> </key>

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/script_Document_guessMimeType.py

@@ -2,7 +2,7 @@ document = state_change['object']
 portal = document.getPortalObject()
 
 filename = document.getFilename()
-content_type = portal.mimetypes_registry.lookupExtension(filename)
-
-if content_type is not None:
-  document.setContentType(str(content_type))
+if filename:
+  content_type = portal.mimetypes_registry.lookupExtension(filename)
+  if content_type is not None:
+    document.setContentType(str(content_type))