When storing old versions of files for use in generating new files via

patching and for rolling back updates, don't copy a file if it has already
been stored.  This provides a significant speedup to the "Preparing to
download files" stage of "freebsd-update fetch" if many updates have already
been applied or if a file being updated is linked many times (such as
/rescue/*).

Reported by:	Paul Dekkers
MFC after:	1 week
Approved by:	re (bmah)

0 files changed, 0 insertions, 0 deletions