Tweak backup scripts to ensure sudo -H is effectively in use

rattail_fabric2/deploy/backup/rattail-backup.mako

@@ -8,6 +8,15 @@ else
     CONFIG='/srv/envs/${envname}/app/silent.conf'
 fi
 
+# sanity check
+if [ "$HOME" != '/root' ]; then
+    echo ''
+    echo '$HOME is not /root - please run this as e.g.:'
+    echo ''
+    echo '   sudo -H rattail-backup [--verbose]'
+    exit 1
+fi
+
 cd /srv/envs/${envname}
 
 bin/rattail -c $CONFIG $VERBOSE backup $*