--- a/cubicweb/dataimport/importer.py	Wed May 22 11:34:08 2019 +0200
+++ b/cubicweb/dataimport/importer.py	Fri May 24 16:29:14 2019 +0200
@@ -71,7 +71,10 @@
     def use_extid_as_cwuri_filter(extentities):
         for extentity in extentities:
             if extentity.extid not in extid2eid:
-                extentity.values.setdefault('cwuri', set([extentity.extid.decode('utf-8')]))
+                cwuri = extentity.extid
+                if isinstance(cwuri, bytes):
+                    cwuri = cwuri.decode('utf-8')
+                extentity.values.setdefault('cwuri', set([cwuri]))
             yield extentity
     return use_extid_as_cwuri_filter