https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=804249
https://sources.debian.org/patches/python-setuptools/40.8.0-1/sorted-requires.diff/

Index: b/setuptools/command/egg_info.py
===================================================================
--- a/setuptools/command/egg_info.py
+++ b/setuptools/command/egg_info.py
@@ -641,7 +641,7 @@ def _write_requirements(stream, reqs):
 
     def append_cr(line):
         return line + '\n'
-    lines = map(append_cr, lines)
+    lines = map(append_cr, sorted(lines))
     stream.writelines(lines)
 
 
