so that files named all.py and catalog.py are ignored.

see

https://help.semmle.com/lgtm-enterprise/user/help/lgtm.yml-configuration-file.html#path_classifiers

CC: @embray @kiwifb @isuruf @tscrim

Component: refactoring

Author: Frédéric Chapoton

Branch/Commit: 967c510

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/28995