Merge branch 'jk/dont-count-existing-objects-twice'

There is a logic to estimate how many objects are in the
repository, which is mean to run once per process invocation, but
it ran every time the estimated value was requested.

* jk/dont-count-existing-objects-twice:
  packfile: actually set approximate_object_count_valid

packfile.c

@@ -923,6 +923,7 @@ unsigned long repo_approximate_object_count(struct repository *r)
 			count += p->num_objects;
 		}
 		r->objects->approximate_object_count = count;
+		r->objects->approximate_object_count_valid = 1;
 	}
 	return r->objects->approximate_object_count;
 }

t/perf/p5303-many-packs.sh

@@ -73,6 +73,10 @@ do
 		git rev-list --objects --all >/dev/null
 	'
 
+	test_perf "abbrev-commit ($nr_packs)" '
+		git rev-list --abbrev-commit HEAD >/dev/null
+	'
+
 	# This simulates the interesting part of the repack, which is the
 	# actual pack generation, without smudging the on-disk setup
 	# between trials.