shelve: be quiet when unshelve pulls from the shelve bundle
unshelve was quite verbose and it was hard for a user to follow what really was
going on. It ended up saying 'added 1 changesets' ... but the user just
expected and got pending changes and never saw any changeset.
The use of bundles is an implementation detail that we don't have to leak here.
Pulling is quite verbose, optimized for pulling many changesets from remote
repos - that is not the case here.
Instead, set the quiet flag when pulling the bundle - not only when temporarily
committing pending changes.
The 'finally' restore of ui.quiet is moved to the outer try/finally used for
locking.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.