Unexpected nonzero return code from .py utilities with --help or --version

[plimkilde]

Expected behavior and actual behavior.

Some of the .py utilities of GDAL (gdalattachpct.py, gdal_sieve.py etc.) return a nonzero code when called with --help and/or --version. This is rather problematic in CI, see conda-forge/gdal-feedstock#835 and conda-forge/gdal-feedstock#853.

Some of these utilities were fixed in #8676, but a few still have issues. I've systematically tested GDAL 3.8.0 with the results below:

Command	With --help	With --version
rgb2pct.py	0	0
pct2rgb.py	0	0
gdalattachpct.py	2	2
gdal_merge.py	0	0
gdal2tiles.py	0	0
gdal2xyz.py	0	0
gdal_retile.py	0	0
gdal_proximity.py	0	0
gdal_polygonize.py	0	0
gdal_sieve.py	2	0
gdal_fillnodata.py	0	0
gdalmove.py	2	0
gdal_edit.py	0	0
gdal_calc.py	0	0
gdal_pansharpen.py	0	0
gdalcompare.py	2	0
ogrmerge.py	0	0
ogr_layer_algebra.py	0	0

Steps to reproduce the problem.

Call
NAME_OF_THE_UTILITY.py --help
or
NAME_OF_THE_UTILITY.py --version
and check the return value.

Operating system

Tested on Windows 10, x86-64, but is probably cross-platform.

GDAL version and provenance

Tested with GDAL 3.8.0 from conda-forge, build py312hb5f3cee_1.