setup.bash silently fails on conda/pixi prefixes: _local_setup_util_sh.py not found in chained prefix

[antrom99]

Environment

• OS: macOS Sequoia (Apple Silicon, osx-arm64)
• Shell: zsh
• ROS 2 Humble via RoboStack + Pixi
• Python: 3.12 (.pixi/envs/humble/bin/python3.12)
• colcon-core: latest

Steps to Reproduce

1. Set up a ROS 2 workspace using RoboStack via Pixi (conda-based environment)
2. Run colcon build --packages-up-to <package>
3. Run source install/setup.bash

Actual Behavior

The command silently exits without error code, but the environment is not sourced correctly. With tracing enabled, the failure is:

/path/to/.pixi/envs/humble/bin/python3.12: \
  can't open file '/path/to/.pixi/envs/humble/_local_setup_util_sh.py': \
  [Errno 2] No such file or directory

Expected Behavior

setup.bash should source correctly, or emit a clear error when a chained prefix does not contain _local_setup_util_sh.py.

Root Cause

install/setup.bash chains two prefixes (lines 22–26):

1. .pixi/envs/humble — the conda/RoboStack ROS 2 base prefix
2. install/ — the colcon workspace prefix

For each prefix, local_setup.bash invokes:

$_colcon_python_executable \
  "$_colcon_prefix_bash_COLCON_CURRENT_PREFIX/_local_setup_util_sh.py" \
  sh bash

colcon generates _local_setup_util_sh.py only in install/. When processing the first chained prefix (.pixi/envs/humble), Python looks for the file there — but it does not exist because that prefix was installed via conda/pixi, not colcon. The failure is silent because the exit code is swallowed.

Workaround

ln -sf install/_local_setup_util_sh.py .pixi/envs/humble/_local_setup_util_sh.py
ln -sf install/_local_setup_util_ps1.py .pixi/envs/humble/_local_setup_util_ps1.py
source install/setup.bash

Proposed Fix

Add a guard in local_setup.bash before invoking Python, so non-colcon prefixes are skipped gracefully:

if [ -f "$_colcon_prefix_bash_COLCON_CURRENT_PREFIX/_local_setup_util_sh.py" ]; then
  _colcon_ordered_commands="$($_colcon_python_executable \
    "$_colcon_prefix_bash_COLCON_CURRENT_PREFIX/_local_setup_util_sh.py" sh bash)"
fi

Related

• setup.bash scripts are not completely relocatable #431 — setup.bash scripts are not completely relocatable
• source install/setup.bash, no such file or directory RoboStack/ros-humble#272 — user report of the same symptom