When doing a copy (no delete mode) without a logger, the destination
listing can be cancelled as soon as the source listing finishes, since
dst-only entries won't be processed.
This is particularly beneficial with --fast-list where the dst listing
may fetch the entire directory tree upfront via ListR. Cancelling it
early avoids waiting for a potentially large listing that won't be used.
Adds NoProcessDstOnly flag to March which, when set, cancels the dst
listing context once the source channel is exhausted in matchListings.
Fixes#9226
Nick Craig-Wood
9e0a5b66a4