distributed-bakery: can't run --customer-id 2: `Result::unwrap()` on an `Err` value: Unexpected(None)

[bbigras]

I can start the first one with cargo run --release --example distributed-bakery --features="tokio" -- --bootstrap --customer-id "1", but the second one gives this error:

RUST_BACKTRACE=1 cargo run --release --example distributed-bakery --features="tokio" -- --customer-id "2"

thread 'tokio-runtime-worker' panicked at examples/distributed_bakery.rs:154:47:
called `Result::unwrap()` on an `Err` value: Unexpected(None)
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::result::unwrap_failed
   3: automerge_repo::dochandle::DocHandle::with_doc_mut
   4: distributed_bakery::main::{{closure}}::{{closure}}
   5: tokio::runtime::task::core::Core<T,S>::poll
   6: tokio::runtime::task::harness::Harness<T,S>::poll
   7: tokio::runtime::scheduler::multi_thread::worker::Context::run_task
   8: tokio::runtime::scheduler::multi_thread::worker::Context::run
   9: tokio::runtime::context::scoped::Scoped<T>::set
  10: tokio::runtime::context::runtime::enter_runtime
  11: tokio::runtime::scheduler::multi_thread::worker::run
  12: <tokio::runtime::blocking::task::BlockingTask<T> as core::future::future::Future>::poll
  13: tokio::runtime::task::core::Core<T,S>::poll
  14: tokio::runtime::task::harness::Harness<T,S>::poll
  15: tokio::runtime::blocking::pool::Inner::run
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

9b0ca93 is the first bad commit