Remove kludges that map EEXIST errors too a 0 return (success) for certain operations (non-idempotent ones) under the assumption that the reply from the server is for a duplicate of the original request.
Remove kludges that map EEXIST errors too a 0 return (success) for certain
operations (non-idempotent ones) under the assumption that the reply from
the server is for a duplicate of the original request.

However, most (all) NFS server today have a duplicate reply cache that
address this problem and these kludges have been shown to cause problems
with some applications (most notably dovecot as pointed out by brad@).

For more information:
http://lists.freebsd.org/pipermail/freebsd-current/2007-November/079961.html
And revision 1.277 of sys/nfsclient/nfs_vnops.c in FreeBSD.

Diff from rwatson@freebsd.org

OK blambert@, "no objections" krw@
tested by many;

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars