[py3][json] json.dumps returns text type

--HG--
branch : 0.1

cubicweb_jsonschema/api/entities.py

@@ -17,6 +17,8 @@
 """cubicweb-jsonschema Pyramid views for the JSON API of entities."""
 import json
 
+from six import PY3
+
 from pyramid import httpexceptions
 from pyramid.renderers import render
 from pyramid.view import view_config
@@ -345,7 +347,10 @@ def generic_error(exc, request):
     if isinstance(exc, httpexceptions.HTTPException):
         if exc.content_type != 'application/json':
             exc.content_type = 'application/json'
-            exc.body = json.dumps({'message': exc.detail})
+            body = json.dumps({'message': exc.detail})
+            if PY3:
+                body = body.encode('utf-8')
+            exc.body = body
         return exc
     request.cw_cnx.rollback()
     LOG.exception('exception occurred while processing %s', request)