meta::Cache::reset can panic

[fuchsnj]

What version of regex are you using?

Latest / 0.4.4

Describe the bug at a high level.

Calling .reset(..) on a meta::Cache can panic if called on a different regex than it was created with (which is the whole point of reset).

What are the steps to reproduce the behavior?

use regex_automata::meta::Regex;

fn main() {
    let re1 = Regex::new("").unwrap();
    let re2 = Regex::new("\\b").unwrap();
    re1.create_cache().reset(&re2);
}

What is the actual behavior?

thread 'main' panicked at /playground/.cargo/registry/src/index.crates.io-6f17d22bba15001f/regex-automata-0.4.3/src/meta/wrappers.rs:507:29:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0: rust_begin_unwind
             at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:645:5
   1: core::panicking::panic_fmt
             at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:72:14
   2: core::panicking::panic
             at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:127:5
   3: core::option::Option<T>::unwrap
             at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/option.rs:931:21
   4: regex_automata::meta::wrappers::OnePassCache::reset
             at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/regex-automata-0.4.3/src/meta/wrappers.rs:507:13
   5: <regex_automata::meta::strategy::Core as regex_automata::meta::strategy::Strategy>::reset_cache
             at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/regex-automata-0.4.3/src/meta/strategy.rs:688:9
   6: regex_automata::meta::regex::Cache::reset
             at ./.cargo/registry/src/index.crates.io-6f17d22bba15001f/regex-automata-0.4.3/src/meta/regex.rs:2385:9
   7: playground::main
             at ./src/main.rs:6:5
   8: core::ops::function::FnOnce::call_once
             at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

What is the expected behavior?

It should not panic, and allow using that cache on the new regex.

Additional info

One example of a location this panics is: https://github.com/rust-lang/regex/blob/master/regex-automata/src/meta/wrappers.rs#L799
although it looks like other reset implementations have similar issues.