Is python-argparse dependency still necessary?

[kenji-miyake]

According to https://github.com/ros/rosdistro/blob/master/rosdep/python.yaml#L471-L498, it seems it's only for older distributions.

I think in most of the distributions that are currently supported, we can use argparse without installing any packages.

$ docker run --rm -it ubuntu:18.04 /bin/bash # or 16.04
# apt update && apt install -y python
# python
Python 2.7.17 (default, Apr 15 2020, 17:20:14) 
[GCC 7.5.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import argparse
>>> 

I'm asking this because it causes an error when using colcon-ros-bundle to mrt_cmake_modules.
When dependency.name is python-argparse, rule and package_name_list will be [], so an error happens.
https://github.com/colcon/colcon-ros-bundle/blob/master/colcon_ros_bundle/task/ros_bundle.py#L62-L66

Of course, I'll send an issue/PR to colcon-ros-bundle, but it would be helpful if you could remove this old dependency.

[poggenhans]

We were just trying to be correct, but since argparse seems to be part of the standard library in python 2.7 and above, I guess we can just remove it.

For alpine, it is even wrong, I just noticed. py-argparse actually installs python3.