benchmarks.md and catalog_open.rs both said schema::backfill runs on
every Catalog::open. Since ffdd640 it runs on the first open of a path
in a process and is skipped while the stamp matches, so in dr-bench
catalog_open_ms still includes it and catalog_open_warm_ms, the second
open in the same process, no longer does. That is what a library
reopened in one session costs, and both now say which figure is which.
The comment keeps its line count, so no tag below it moves.
dtourolle
1b8d0e740f