diff -r 6b3523f81f42 -r 26744ad37953 cubicweb/server/ssplanner.py
--- a/cubicweb/server/ssplanner.py	Fri Apr 05 17:21:14 2019 +0200
+++ b/cubicweb/server/ssplanner.py	Fri Apr 05 17:58:19 2019 +0200
@@ -17,8 +17,6 @@
 # with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
 """plan execution of rql queries on a single source"""
 
-from six import text_type
-
 from rql.stmts import Union, Select
 from rql.nodes import Constant, Relation
 
@@ -55,7 +53,7 @@
                 value = rhs.eval(plan.args)
                 eschema = edef.entity.e_schema
                 attrtype = eschema.subjrels[rtype].objects(eschema)[0]
-                if attrtype == 'Password' and isinstance(value, text_type):
+                if attrtype == 'Password' and isinstance(value, str):
                     value = value.encode('UTF8')
                 edef.edited_attribute(rtype, value)
             elif str(rhs) in to_build: