diff -r e94287ab06d4 -r f758bc424dc9 cubicweb/_exceptions.py
--- a/cubicweb/_exceptions.py	Thu May 16 04:47:10 2019 +0200
+++ b/cubicweb/_exceptions.py	Thu May 16 04:47:27 2019 +0200
@@ -20,7 +20,7 @@
 
 from logilab.common.decorators import cachedproperty
 
-from yams import ValidationError
+from yams import ValidationError  # noqa: F401
 
 # abstract exceptions #########################################################