Error in reset_ctrl ?

https://github.com/abseil/abseil-cpp/blob/43ef2148c0936ebf7cb4be6b19927a9d9d145b8f/absl/container/internal/raw_hash_set.h#L1717

The length of ctrl_ is capacity + width + 1, and your comment says set it all to empty, except the last element, to sentinel.
You are setting it all to empty, except the last element, but instead of setting the last element to sentinel, you are ignoring width.
So:
ctrl_[capacity_] = kSentinel;
==>
ctrl_[capacity_ + Group::kWidth] = kSentinel;