Clarify that core.deltaBaseCacheLimit is per-thread, as can be seen from
the fact that cache usage (base_cache_used in struct thread_local in
builtin/index-pack.c) is tracked individually for each thread and
compared against delta_base_cache_limit.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>