Fix ssh-keyscan in new backup script

ROOT/DEBIAN/control

@@ -3,7 +3,7 @@ Priority: optional
 Section: otherosfs
 Maintainer: Frank Lee <rl201@cam.ac.uk>
 Architecture: all
-Version: 0.9-ch21
+Version: 0.9-ch22
 Depends: debian-zfs, postgresql, liblockfile-simple-perl, libdbi-perl, libjson-perl, libzfs-perl-chem, libnet-openssh-perl, libdbd-pg-perl, mbuffer
 Description: a backup system using ZFS
  Ported (well, mostly) from FreeBSD to a Sane OS.

ROOT/usr/lib/chem-zfs-backup-server/new-backup-rsnapshot

@@ -114,7 +114,7 @@ function backupdir() {
 
 function getsshkey() {
   FQDN=$1
-  ssh-keyscan -t ecdsa $FQDN >> /root/.ssh/known_hosts
+  ssh-keyscan $FQDN 2>/dev/null >> /root/.ssh/known_hosts
 }