I had the same issue, so I use try and except block to fix this problem in python 3.3 in blender 2.69.
Solution
try:
args = parser.parse_args(argv)
do_something(args)
except SystemExit as e:
print(repr(e))
# END OF FILE
Results
When we run blender like this:
blender -b -P argparse_blender.py -- -h
We get the desired output:
usage: blender [-h]
Run blender in background mode with this script: blender --background --python argparse_blender.py -- [options]
optional arguments:
-h, --help show this help message and exit
SystemExit(0,)
found bundled python: [...]/blender/2.69/python
Blender quit
Suggestion
I would write the whole thing like this:
import do_something
import argparse
import sys
argv = sys.argv
if "--" not in argv:
argv = []
else:
argv = argv[argv.index("--") + 1:]
## set the prog name to match real usage
parser = argparse.ArgumentParser(
description = 'Run blender in background mode',
prog = "blender -b -P "+__file__+" --",
)
try:
args = parser.parse_args(argv)
do_something(args)
except SystemExit as e:
print(repr(e))
# END OF FILE
Because it gives nicer output:
usage: blender -b -P argparse_blender.py -- [-h]
Run blender in background mode
optional arguments:
-h, --help show this help message and exit
SystemExit(0,)
found bundled python: [...]/blender/2.69/python
Blender quit