Fix for join_into status result when root value is changed

[luketpeterson]

Fix for #139

Very straightforward fix.

[github-actions]

Bench A/B vs base: done

job log · 2026-09-27 03:30:44 UTC

base e4b167c → head 2f15446, 3 round(s), median of each run averaged; negative is faster

bench	cases	geomean	largest gain	largest loss	>5% faster	>5% slower
shakespeare	7	+0.1%	-3.7% shakespeare/shakespeare_sentences_get	+6.1% shakespeare/shakespeare_words_val_count	0	1
cities	5	+0.2%	-4.6% cities/cities_val_count	+3.5% cities/cities_get	0	0
sparse_keys	96	-0.1%	-3.3% sparse_zipper_cursor/400	+4.0% sparse_get/1000	0	0
binary_keys	77	-0.5%	-5.7% binary_descend_until/1000	+10.8% binary_insert/1600	1	4
superdense_keys	104	-0.4%	-4.2% superdense_val_count_bench_act/100	+4.4% superdense_val_count_bench/20000	0	0
act_paths	46	-0.3%	-6.8% shape_inflate_only/dense_wide	+6.6% size_dense_paths_to_act/25000	3	6
zipper_head_owned	12	+0.1%	-1.7% borrowed_head_read_creation/10	+3.3% owned_head_write_creation_cleanup/1	0	0
product_zipper	4	-1.5%	-3.3% product_zipper/introspecting_pathmap_pathmap	+0.2% product_zipper/generic_act_act	0	0

15 case(s) moved more than 5%

bench	case	base	head	change
binary_keys	binary_insert/1600	168.30 µs	186.40 µs	+10.8%
binary_keys	binary_insert/50	3.44 µs	3.77 µs	+9.5%
binary_keys	binary_insert/100	7.45 µs	8.02 µs	+7.6%
act_paths	shape_inflate_only/dense_wide	2.62 ms	2.44 ms	-6.8%
act_paths	size_dense_paths_to_act/25000	850.60 µs	907.13 µs	+6.6%
shakespeare	shakespeare/shakespeare_words_val_count	316.07 µs	335.50 µs	+6.1%
act_paths	shape_paths_to_act/dense_wide	6.76 ms	7.17 ms	+6.1%
act_paths	shape_paths_to_act/clustered	7.14 ms	7.58 ms	+6.1%
binary_keys	binary_insert/200	15.95 µs	16.90 µs	+6.0%
binary_keys	binary_descend_until/1000	68.49 µs	64.62 µs	-5.7%
act_paths	shape_map_to_act_cata/dense_narrow	10.44 ms	9.85 ms	-5.6%
act_paths	shape_map_to_act_cata/random_long	51.12 ms	48.25 ms	-5.6%
act_paths	size_dense_paths_to_act/400000	13.54 ms	14.27 ms	+5.4%
act_paths	size_dense_paths_to_act/800000	26.36 ms	27.77 ms	+5.4%
act_paths	size_dense_paths_to_act/200000	6.78 ms	7.14 ms	+5.3%

Full tables per bench are in the job log and the bench-out artifact.