I started to look at the Python gnulib-tool and ran into this error that
should be easily reproducible:

[collin@debian src]$ gnulib-tool.py --create-testdir --dir test dummy
Module list with included dependencies (indented):
  dummy
File list:
  lib/dummy.c
  m4/00gnulib.m4
  m4/gnulib-common.m4
  m4/zzgnulib.m4
Traceback (most recent call last):
  File "/home/collin/.local/bin/gnulib-tool.py", line 1171, in <module>
    main()
  File "/home/collin/.local/bin/gnulib-tool.py", line 908, in main
    testdir.execute()
  File "/home/collin/.local/src/gnulib/pygnulib/GLTestDir.py", line 503,
in execute
    self.config.setAuxDir(saved_auxdir)
                          ^^^^^^^^^^^^
NameError: name 'saved_auxdir' is not defined

I commented out the offending line instead of removing it just in case
it is useful in the future. The previous command should work with the
dummy module so I can start comparing the output while learning the code.