This change is probably not a proper fix, somebody with more expertise on
this code should look at it.
Here is how to reproduce the crash:
- start with a layout with two zones
- move all nodes of a zone to gateway mode: `garage layout assign fea54bcc081f318 -g`
- `garage layout show` will panic with a backtrace
Fortunately, the crash is only on the RPC client side, not on the Garage
server itself, and `garage layout revert` still works to go back to the
previous state.
As far as I can tell, this bug is present since Garage 0.9.0 which
includes the new layout assignation algorithm:
https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/296
rmoff