[fstagni]

Summary

Merges devel into master for production. Content-wise this is two fixes + one CI sync (already on master via cherry-pick e29b526):

 Pilot/pilotTools.py        # genericOption (str) -> genericOptions (list), fixes #284
 Pilot/pilotCommands.py     # consume genericOptions; purge installEnv before repopulating, fixes #156
 Pilot/tests/Test_Pilot.py  # test: multiple -o/--option all take effect
 .github/workflows/nightly.yml  # retention-days 1 -> 3 (same change as e29b526, already on master)

• PR Make genericOptions a list #285 / [Bug]: genericOptions should be a list of options but only last given option takes effect #284: repeated -o/--option pilot arguments all take effect (previously only the last one).
• PR purge the site installEnv variables #286 / Purging variables in pilotCommand installEnv #156: site-provided environment variables are purged from installEnv before repopulation, restoring pre-[devel] Small refactor to increase adaptability  #203 behaviour.
• e64e269 (retention-days 1→3) is patch-equivalent to e29b526 already on master; master is otherwise fully contained in devel (verified with git cherry).

Evidence

• Both PRs merged into devel with 8 checks passing (Make genericOptions a list #285 on Aug 25, purge the site installEnv variables #286 on Sep 23).
• New regression test in Pilot/tests/Test_Pilot.py: PilotParams() with --option diracInstallOnly -o /LocalSite/Example=value yields genericOptions == ["diracInstallOnly", "/LocalSite/Example=value"].
• No stale references to the old genericOption attribute remain.
• Certification testing per the PR Make genericOptions a list #285 discussion (integration tests pass for LHCb with the LHCbPilot backward-compatibility fix already in production).

Merge Danger

Door: two-way — revertable by reverting the merge commit, but pilot behaviour changes are user-visible immediately on production pilots.

Blast Radius: all pilots. The -o handling change (substring → exact membership for diracInstallOnly/cvmfsOnly, and all options now forwarded) affects every pilot invocation; requires the LHCbPilot backward-compatibility fix to be in production. The installEnv purge changes the environment later pilot commands run in (no longer inheriting the full site environment).

[fstagni]

Integration tests green on the fork: https://github.com/fstagni/Pilot/actions/runs/39435601665 (second attempt; the first one failed on a GitHub API rate-limit flake in the workflow, unrelated to this change). Merging to master.