title: winston logger 2 to 3 upgrade. comma separated messages no longer concatenate
body: <p>I am trying to upgrade from winston 2 to 3 due to a problem with stringifying mongoose nested objects. It caused a recursive call, and crashed... (I will open an issue later for winston2).  instead of changing my code everywhere to stringify, I tried upgrading winston. This fixed the problem and it prints successfully. however, my code also contains places where code such as this exists
  logger.info("got some object like so", { some object })
  this no longer works in winston 3. it only prints the first part. </p>
  
  <p>winston2 code example:</p>
  
  <pre><code>const winston = require('winston');
  
  
  // logger configuration
  var logger = new winston.Logger({
    transports: [
      new winston.transports.Console({
        level:'info',
        handleExceptions: false,
        json: false,
        colorize: true,
        prettyPrint: true
      })
    ],
    exitOnError: false
  });
  
  
  
  logger.info('test1',{'test':'test2'}, 'test3?');
  </code></pre>
  
  <p>output is:</p>
  
  <pre><code>info: test1 { test: 'test2' } test3?
  </code></pre>
  
  <p>as expected</p>
  
  <p>winston3 code:</p>
  
  <pre><code>const winston = require('winston');
  
  
  const prettyJson = winston.format.printf(info =&gt; {
    if (info.message.constructor === Object) {
      info.message = JSON.stringify(info.message, null, 4)
    }
    console.log(info)
    return `${info.timestamp} ${info.level}: ${info.message}`
  });
  
  var logger = winston.createLogger({
      transports:[
          // transport that prints logs into the console
      new winston.transports.Console({
        level: 'info',
        format: winston.format.combine(
            // winston.format.timestamp(),
            // winston.format.colorize(),
            // winston.format.prettyPrint(),
            // winston.format.splat(),
          winston.format.simple(),
  
            // prettyJson
        )
      })
      ]
  });
  
  
  logger.info('test1',{'test':'test2'}, 'test3?');
  </code></pre>
  
  <p>output: <code>info: test1 {"test":"test2"}</code></p>
  
  <p>no matter what i try, i cannot repeat the same output of winston2.</p>