Fix sensitivity of tls13-compat.sh to the exact generation method

Fix `tls13-compat.sh` changing based on exactly how
`generate_tls13_compat_tests.py` was run (e.g. from which directory). This
made `check-generated-files.sh` behave differently from `make`. The script
has no official variations of the content of its output file, so we don't
need to record the full command line.

Signed-off-by: Gilles Peskine <[email protected]>

tests/scripts/generate_tls13_compat_tests.py

@@ -526,11 +526,8 @@ def generate_hrr_compat_test(client=None, server=None,
 
 SSL_OUTPUT_HEADER = '''\
 # TLS 1.3 interoperability test cases (equivalent of compat.sh for TLS 1.3).
-# They are generated by
-# `{cmd}`.
 #
-# PLEASE DO NOT EDIT THIS FILE. IF NEEDED, PLEASE MODIFY `generate_tls13_compat_tests.py`
-# AND REGENERATE THIS FILE.
+# Automatically generated by {cmd}. Do not edit!
 
 # Copyright The Mbed TLS Contributors
 # SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
@@ -621,7 +618,8 @@ def get_all_test_cases():
         if args.output:
             with open(args.output, 'w', encoding="utf-8") as f:
                 f.write(SSL_OUTPUT_HEADER.format(
-                    filename=os.path.basename(args.output), cmd=' '.join(sys.argv)))
+                    filename=os.path.basename(args.output),
+                    cmd=os.path.basename(sys.argv[0])))
                 f.write(DATA_FILES_PATH_VAR)
                 f.write('\n\n'.join(get_all_test_cases()))
                 f.write('\n')