Fix key leakage in SSH deploy log

deploy/ssh.sh

@@ -101,7 +101,7 @@ ssh_deploy() {
   fi
 
   # CERTFILE is optional.
-  # If provided then private key will be copied or appended to provided filename.
+  # If provided then certificate will be copied or appended to provided filename.
   if [ -n "$DEPLOY_SSH_CERTFILE" ]; then
     Le_Deploy_ssh_certfile="$DEPLOY_SSH_CERTFILE"
     _savedomainconf Le_Deploy_ssh_certfile "$Le_Deploy_ssh_certfile"
@@ -190,7 +190,7 @@ then rm -rf \"\$fn\"; echo \"Backup \$fn deleted as older than 180 days\"; fi; d
     _info "Backup directories erased after 180 days."
   fi
 
-  _debug "Remote commands to execute: $_cmdstr"
+  _secure_debug "Remote commands to execute: " "$_cmdstr"
   _info "Submitting sequence of commands to remote server by ssh"
   # quotations in bash cmd below intended.  Squash travis spellcheck error
   # shellcheck disable=SC2029