fix exit code capture from handlers

src/backupninja.in

@@ -375,8 +375,8 @@ function process_action() {
                [ $debug ] && colorize "$a"
             done
          )
-         retcode=$?
-         # ^^^^^^^^ we have a problem! we can't grab the return code "$?". grrr.
+         retcode=${PIPESTATUS[0]}
+         debug "handler returned exit code $retcode"
          echo_debug_msg=0
 
       else