* wdclient: keep the location of a volume reported added and removed at once
A volume moved between a server's disks arrives in both lists of one message,
and the server still has it. Additions were applied before removals, so the
removal won and the client was left with no location for a volume that never
went anywhere.
Reordering would swap the bug for a window where the volume resolves nowhere,
since the two updates take the lock separately. Skip the removal instead, so
the order the lists are applied in stops mattering.
* wdclient: build each ec update explicitly in the move test
Reusing one response object and adding the deletion to it left the overlap the
test turns on implicit, and reading it as a delete-only update is the natural
mistake.