scripts: print usage in argparse-using scripts when a command-line error occurs

For scripts that use Python's standard argparse module to parse
command-line arguments, create a subclass which will show the usage
the usage information when a command-line parsing error occurs. The most
common case would be when the script is run with no arguments; at least
then the user immediately gets to see what arguments they might need to
pass instead of just an error message.

(From OE-Core rev: d62fe7c9bc2df6a4464440a3cae0539074bf99aa)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/argparse_oe.py

@@ -0,0 +1,11 @@
+import sys
+import argparse
+
+class ArgumentParser(argparse.ArgumentParser):
+    """Our own version of argparse's ArgumentParser"""
+
+    def error(self, message):
+        sys.stderr.write('ERROR: %s\n' % message)
+        self.print_help()
+        sys.exit(2)
+

scripts/lib/scriptutils.py

@@ -19,6 +19,7 @@ import sys
 import os
 import logging
 import glob
+import argparse
 
 def logger_create(name):
     logger = logging.getLogger(name)