make sure to raise an error if pick_python_cmd returns False for Python bundles/packages

[casparvl]

This was already done for PythonPackage, but not for PythonBundle. I ran into this here easybuilders/easybuild-easyconfigs#21307 (comment)

[casparvl]

When used with ReFrame-4.9.2.eb from easybuilders/easybuild-easyconfigs#21307 , with this PR, a proper error is raised:

== 2024-09-03 21:20:47,564 run.py:247 INFO running cmd: /usr/bin/python3 -c 'import sys; print("%s.%s.%s" % sys.version_info[:3])'
== 2024-09-03 21:20:47,591 run.py:689 DEBUG cmd "/usr/bin/python3 -c 'import sys; print("%s.%s.%s" % sys.version_info[:3])'" exited with exit code 0 and output:
3.6.8

== 2024-09-03 21:20:47,591 run.py:725 DEBUG Using default regular expression: (?<![(,-]|\w)(?:error|segmentation fault|failed)(?![(,-]|\.?\w)
== 2024-09-03 21:20:47,591 pythonpackage.py:130 DEBUG Minimal requirement for minor Python version not satisfied: 3.6.8 vs 3.7
== 2024-09-03 21:20:47,591 pythonpackage.py:159 DEBUG Python command '/usr/bin/python3' does not satisfy version requirements (maj: 3, min: 7), moving on
== 2024-09-03 21:20:47,611 build_log.py:171 ERROR EasyBuild crashed with an error (at easybuild/base/exceptions.py:126 in __init__): Failed to pick Python command to use (at easybuild/easyblocks/generic/pythonbundle.py:115 in prepare_step)
== 2024-09-03 21:20:47,612 build_log.py:267 INFO ... (took < 1 sec)
== 2024-09-03 21:20:47,615 config.py:700 DEBUG software install path as specified by 'installpath' and 'subdir_software': /home/it4i-casparl/.local/easybuild/software
== 2024-09-03 21:20:47,615 filetools.py:2013 INFO Removing lock /home/it4i-casparl/.local/easybuild/software/.locks/_home_it4i-casparl_.local_easybuild_software_ReFrame_4.6.2.lock...
== 2024-09-03 21:20:47,616 filetools.py:383 INFO Path /home/it4i-casparl/.local/easybuild/software/.locks/_home_it4i-casparl_.
local_easybuild_software_ReFrame_4.6.2.lock successfully removed.
== 2024-09-03 21:20:47,616 filetools.py:2017 INFO Lock removed: /home/it4i-casparl/.local/easybuild/software/.locks/_home_it4i-casparl_.local_easybuild_software_ReFrame_4.6.2.lock
== 2024-09-03 21:20:47,616 easyblock.py:4285 WARNING build failed (first 300 chars): Failed to pick Python command to use

Although it is still cryptic (it doesn't specifically complain about the version unless you run with --debug), at least behavior is now the same as for PythonPackage. And: at least EasyBuild doesn't just try to run a python command that doesn't exist on the system.

[casparvl]

Test build in easybuilders/easybuild-easyconfigs#21307 (comment) (ended up in the other PR... but still shows it in the gist all right: https://gist.github.com/casparvl/07e98bf3cb8c43ee1a6f34a38b1eed6d . It now

1. errors out also for pythonbundle and
2. the error is more clear on the fact that there is a requirement for the python versions in the EasyConfigs (and that that might be why no valid python command is found)

[bedroge]

Test report by @bedroge

Overview of tested easyconfigs (in order)

• FAIL (build issue) ReFrame-4.6.2.eb (partial log available at https://gist.github.com/bedroge/d99ddfdd92ae3a5beac6b7d85835ef41)

Build succeeded for 0 out of 1 (1 easyconfigs in total)
interactive1 - Linux Rocky Linux 8.9, x86_64, AMD EPYC-Milan Processor (zen3), Python 3.6.8
See https://gist.github.com/bedroge/658cf22fd1c22abb32ca8337a5027899 for a full test report.

This is an expected failure to demonstrate that the added functionality works: I tried building the ReFrame version from easybuilders/easybuild-easyconfigs#21307 using Python 3.6, while it needs at least 3.7.

== FAILED: Installation ended unsuccessfully (build directory: /dev/shm/p251204/ReFrame/4.6.2/system-system): build failed (first 300 chars): Failed to pick 
python command that satisfies requirements in the EasyConfigs (req_py_majver = 3, req_py_minver = 7) (took 0 secs)

[bedroge]

Test report by @bedroge

Overview of tested easyconfigs (in order)

• SUCCESS pyBigWig-0.3.22-gfbf-2023a.eb
• SUCCESS PyYAML-6.0-GCCcore-12.2.0.eb
• SUCCESS sktime-0.25.0-gfbf-2023a.eb
• SUCCESS NiBabel-4.0.2-foss-2022a.eb

Build succeeded for 4 out of 4 (4 easyconfigs in total)
bob-Latitude-5300 - Linux Ubuntu 24.04.1 LTS (Noble Numbat), x86_64, Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz, Python 3.12.3
See https://gist.github.com/bedroge/390dbacfe8775eb02397ca838813083c for a full test report.

[bedroge]

Test report by @bedroge

Overview of tested easyconfigs (in order)

• SUCCESS ReFrame-4.6.2.eb

Build succeeded for 1 out of 1 (1 easyconfigs in total)
bob-Latitude-5300 - Linux Ubuntu 24.04.1 LTS (Noble Numbat), x86_64, Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz, Python 3.12.3
See https://gist.github.com/bedroge/ddf841dd1329ad5b5c6f7ac561446ff9 for a full test report.

This is the other easyconfig from easybuilders/easybuild-easyconfigs#21307, which requires at least Python 3.7, and 3.12 is being used. So, it also works as expected.

[bedroge]

Lgtm