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
@@ -621,7 +621,7 @@ def warn_depends_obsolete(cmd, basename,
 def _write_requirements(stream, reqs):
     lines = yield_lines(reqs or ())
     append_cr = lambda line: line + '\n'
-    lines = map(append_cr, lines)
+    lines = map(append_cr, sorted(lines))
     stream.writelines(lines)
 
 
