xvfb-run --auto-servernum picks a fresh display number, but if a previous
session left an orphan Xvfb process (e.g. killed mid-flight), the stale
/tmp/.X11-unix/X<N> socket and X<N>-lock still belong to that orphan, and
xvfb-run's cleanup at the end fails with "kill: No such process" — flipping
the script's exit status to non-zero even when the integration test itself
passed. Reap orphan Xvfb processes (pgrep -u $USER -x Xvfb) and remove their
display sockets and lock files before invoking xvfb-run.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
