Restore the plan's if-grep / replace / else-append skeleton in the
CLUSEV_REPOSITORY write-back. The replace branch deletes existing
line(s) then appends once so duplicates collapse to a single entry,
keeping scripts/set-repository-url.test.sh green (the plan's verbatim
in-place sed leaves two identical lines and fails the duplicate-line
assertion).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
boban