deployment: do not overwrite /etc/hosts if it was retrieved from mgmt system

From: Michael Prokop <mprokop@sipwise.com>

deployment.sh

@@ -1301,17 +1301,21 @@ EOF
 
 # append hostnames of sp1/sp2 so they can talk to each other
 # in the HA setup
-if "$PRO_EDITION" ; then
-  cat >> $TARGET/etc/hosts << EOF
+if "$RETRIEVE_MGMT_CONFIG" ; then
+  echo "Nothing to do, /etc/hosts was already set up."
+else
+  if "$PRO_EDITION" ; then
+    cat >> $TARGET/etc/hosts << EOF
 $IP1 sp1
 $IP2 sp2
 EOF
-else
-  # otherwise 'hostname --fqdn' does not work and causes delays with exim4 startup
-  cat >> $TARGET/etc/hosts << EOF
+  else
+    # otherwise 'hostname --fqdn' does not work and causes delays with exim4 startup
+    cat >> $TARGET/etc/hosts << EOF
 # required for FQDN, please adjust if needed
 127.0.0.1 $TARGET_HOSTNAME
 EOF
+  fi
 fi
 
 if [ -n "$PUPPET" ] ; then