DAOS-18905 build: fix in_list PATH check due to missing word-split

[knard38]

Description

This PR fixes two related issues in utils/sl/setup_local.sh.

Commit 1 — word-split bug (d51c4d1027)

setup_local.sh uses the in_list helper to avoid prepending $SL_PREFIX/bin to PATH when it is already present. The guard was broken because $old_path (and $added) were quoted when passed to in_list, so the entire colon-to-space-converted PATH string was passed as a single argument instead of being word-split into individual directories. As a result in_list never found a match and $SL_PREFIX/bin was unconditionally prepended every time setup_local.sh was sourced — even in the same shell session.

The same quoting mistake affected both the per-prefix loop (${added}, ${old_path}) and the final SL_PREFIX/bin check (${old_path}).

Commit 2 — latent set -e hazard (16925e48ce)

Once the word-split fix is in place, in_list correctly returns 1 for the "found" case. However, in_list was called as a standalone statement with its exit code checked afterward via $?. Scripts that source setup_local.sh under set -e (e.g. utils/rpms/build_packages.sh) abort immediately on that non-zero return before the $? check runs.

This was a latent design flaw independent of the quoting bug: in_list should always be called inside an if condition, not as a standalone statement with $? checked afterward. It surfaced here because fixing the quoting made in_list actually return 1 for the first time, triggering the abort in callers like utils/rpms/build_packages.sh — which is why the initial CI run on this PR showed build failures. The two commits are kept separate intentionally: the second independently documents the set -e hazard so it is findable in git log on its own. No explicit validation is needed — the CI passing on the second run is sufficient evidence.

Validation

Both steps below must be run from the repo root (where .build_vars.sh lives after a successful build), as setup_local.sh looks for that file relative to $PWD.

1. Without the fix — check out the base branch before this patch (commit 05984ffd13):

git checkout 05984ffd13
# Source three times and watch PATH grow by one entry each time:
for i in 1 2 3; do
    source utils/sl/setup_local.sh > /dev/null
    echo "source #$i: $(echo "$PATH" | tr ':' '\n' | grep -c install) install entries in PATH"
done

2. With the fix — check out the tip of this branch (commit 16925e48ce):

git checkout 16925e48ce
# Reset PATH to remove any duplicates accumulated above, then repeat:
for i in 1 2 3; do
    source utils/sl/setup_local.sh > /dev/null
    echo "source #$i: $(echo "$PATH" | tr ':' '\n' | grep -c install) install entries in PATH"
done

Without the fix the install entry count grows by one on every source. With the fix it stays constant.

Note: .build_vars.sh must exist in the repo root (generated by a successful build). Without it setup_local.sh exits early and PATH is not modified at all.

Steps for the author:

• Commit message follows the guidelines.
• Appropriate Features or Test-tag pragmas were used.
• Appropriate Functional Test Stages were run.
• At least two positive code reviews including at least one code owner from each category referenced in the PR.
• Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions]

Ticket title is 'setup_local.sh: in_list PATH check always passes due to missing word-split'
Status is 'In Review'
Labels: 'triaged'
https://daosio.atlassian.net/browse/DAOS-18905