Return Code not set on SIGINT

Bug report

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • binaries
• Version or commit hash:
  • foxy
• Client library (if applicable):
  • N/A

Steps to reproduce issue

from launch import LaunchDescription
from launch.actions import ExecuteProcess

def generate_launch_description():
    ld = LaunchDescription()
    ld.add_action(ExecuteProcess(cmd=['sleep', '5']))
    return ld

Expected behavior

• If you run the command sleep 5 normally, it has return code 0.
• If you run it and hit CtrlC, it has the return code 130.
• If you launch the above lunch file normally, it has the return code 0.
• If you run it and hit CtrlC, I expect it to return some non-zero code.

Actual behavior

In actuality, it also returns 0.

Additional information

The return code for launch is set on exceptions but the sigint handler does not set the return code and shutsdown the processes "normally".

The best workaround I came up with is an OnShutdown event handler with an OpaqueFunction to save the value of event.reason but that doesn't seem great.

Start with launch/launch/launch_service.py, especially the SIGINT handler and the exception-based return-code handling linked in the issue. Reproduce the provided ExecuteProcess example on Ubuntu 20.04 with Ctrl-C, then verify that launch exits with a non-zero return code instead of 0.