Fix up `merge_from_succ`.

This function has a variable `changed` that is erroneously used for two
related-but-different purpose:
- to detect if the current element has changed;
- to detect if any elements have changed.

As a result, its use for the first purpose is broken, because if any
prior element changed then the code always thinks the current element
has changed. This is only a performance bug, not a correctness bug,
because we frequently end up calling `assign_unpacked` unnecessarily to
overwrite the element with itself.

This commit adds `any_changed` to correctly distinguish between the two
purposes. This is a small perf win for some benchmarks.

0 files changed, 0 insertions, 0 deletions