contrib/import-checker.py

--- a/contrib/import-checker.py	Wed Aug 01 23:08:18 2018 -0400
+++ b/contrib/import-checker.py	Wed Aug 01 16:05:41 2018 +0200
@@ -36,6 +36,7 @@
     'mercurial.pure.parsers',
     # third-party imports should be directly imported
     'mercurial.thirdparty',
+    'mercurial.thirdparty.attr',
     'mercurial.thirdparty.cbor',
     'mercurial.thirdparty.cbor.cbor2',
     'mercurial.thirdparty.zope',