https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=894215
https://sources.debian.org/patches/python-setuptools/40.8.0-1/PKG-INFO-output-reproducible.diff/

--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -193,7 +193,7 @@ def write_pkg_file(self, file):
             self.long_description_content_type
         )
     if self.provides_extras:
-        for extra in self.provides_extras:
+        for extra in sorted(self.provides_extras):
             write_field('Provides-Extra', extra)