catkin_python_setup() breaks message generation in melodic in install space

[NielsH12]

A package which does the following:

1. call catkin_python_setup()
2. Declare its own messages and call generate_messages

Does not work when sourcing install/setup.bash.

source install/setup.bash
rosmsg info <PKG>/<MSG> -- works
rosmsg md5 <PKG>/<MSG> --breaks

This bug is present in Melodic but I can't reproduce it in Noetic

[gbiggs]

Can you provide a sample package that breaks in Melodic?

[NielsH12]

Sure thing: https://github.com/NielsH12/py_test

[NielsH12]

To test: (using docker)
docker run -it --rm ros:melodic-ros-base-bionic
(inside container)
mkdir -p ws/src && cd ws/src
git clone https://github.com/NielsH12/py_test.git
cd ..
catkin_make install
source install/setup.bash
rosmsg show py_test/MyMsg --works
rosmsg md5 py_test/MyMsg --breaks


-- Repeat steps above but with docker run -it --rm ros:noetic-ros-base-focal and rosmsg md5 works too.
(Edit: ros:noetic-ros-base-focal doesn't have git installed, while melodic-ros-base-bionic does. Weird)

[gbiggs]

Thanks for the sample. I've confirmed the bug.