lint: convert submodule linter test to Python

test/lint/lint-submodule.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+"""
+This script checks for git modules
+"""
+
+import subprocess
+import sys
+
+def main():
+    submodules_list = subprocess.check_output(['git', 'submodule', 'status', '--recursive'],
+                                                universal_newlines = True, encoding = 'utf8').rstrip('\n')
+    if submodules_list:
+        print("These submodules were found, delete them:\n", submodules_list)
+        sys.exit(1)
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main()