Merge branch 'mm/lib-httpd-cgi-safe' into jch

CGI helper scripts used by HTTP-related test scripts have been updated to use atomic filesystem operations, preventing race conditions when Apache handles concurrent requests. * mm/lib-httpd-cgi-safe: t/README: document writing concurrency-safe helpers t/lib-httpd: make http-429 first-request check atomic t/lib-httpd: fix apply-one-time-script race under concurrent requests