In 0c86abab4d `merge_schema` obtained a new flag, `reload`.
Unfortunately, the flag was assigned a default value, which I think is
almost always a bad idea, and indeed it was in this case. When
`merge_schema` is called on shard different than 0, it recursively calls
itself on shard 0. That recursive call forgot to pass the `reload` flag.
Fix this.
5223d32fab