shelve: drop unnecessary backup of dirstate for phase-based case...
shelve: drop unnecessary backup of dirstate for phase-based case
Regular shelve has a hack using an uncommitted transaction that's then
aborted at the end of the operation. It preserves the dirstate across
the abort, however, by saving a backup copy of it. Phase-based shelve
instead commits the transaction, so the hack shouldn't be necessary
there.
Differential Revision:
https://phab.mercurial-scm.org/D5389
