pre raised the shadow-storage cap to 128 GB and wrote the originals only
after the whole loop, so a pre that died mid-way left a raised cap with no
record for post to restore from. The cap must stay raised until post (it
is what keeps the snapshot alive during the update), so an exit trap is
wrong; instead record each original before raising it, and have status
list every recorded cap with the vssadmin command that puts it back when
post is never run.
The gateway stop the review flagged (`pkill -f "hermes gateway"`) is
already scoped: the .sh post runs `hermes gateway stop` under this
HERMES_HOME.
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