scripts/lib/argparse_oe: show self.prog in the error message

This aligns our subclassed error() with that in the original class, using
_print_message and self.prog. Also add a docstring based on the original.

(From OE-Core rev: cf0c5175136966eefde8c0d9aa0679e85779f713)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/argparse_oe.py

@@ -16,8 +16,13 @@ class ArgumentParser(argparse.ArgumentParser):
         super(ArgumentParser, self).__init__(*args, **kwargs)
 
     def error(self, message):
-        sys.stderr.write('ERROR: %s\n' % message)
-        self.print_help()
+        """error(message: string)
+
+        Prints a help message incorporating the message to stderr and
+        exits.
+        """
+        self._print_message('%s: error: %s\n' % (self.prog, message), sys.stderr)
+        self.print_help(sys.stderr)
         sys.exit(2)
 
     def error_subcommand(self, message, subcommand):