add-data after init-cache causes assertion failure in stratisd

[mvollmer]

With stratisd 2.4.2:

# stratis pool create pool0 /dev/sda1
# stratis pool init-cache pool0 /dev/sda2
# stratis pool add-data pool0 /dev/sda3
Execution failed:
stratis attempted communication with the daemon, stratisd, over the D-Bus, but stratisd did not respond in the allowed time. 

In the journal:

Sep 21 15:45:54 dev stratisd[757]: thread 'stratis-wt-965' panicked at 'assertion failed: `(left == right)`
Sep 21 15:45:54 dev stratisd[757]:   left: `Device { major: 253, minor: 9 }`,
Sep 21 15:45:54 dev stratisd[757]:  right: `Device { major: 253, minor: 2 }`', src/engine/strat_engine/thinpool/thinpool.rs:516:9
Sep 21 15:45:54 dev stratisd[757]: stack backtrace:
Sep 21 15:45:54 dev stratisd[757]: note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.