joyent/node — pull request #7402 by xionglun (2014-04-03 08:34:00+00:00)
Title:  Buffer: concat multi buffers

When use `Buffer.concat` like below:
```js
var buf1 = new Buffer('hello');
var buf2 = new Buffer('world');
var buf = Buffer.concat([buf1, buf2], 6);
console.log(buf.toString() + ' : ' + buf.length); // hellow : 6
```
It's ok.
But, if **totalLength** less than ` listBuffers.length - lastBuffer.length ` , it will throw a **RangeError**.
```js
var buf1 = new Buffer('hello');
var buf2 = new Buffer('world');
var buf = Buffer.concat([buf1, buf2], 4); // throw new RangeError
```

I think, if some specified **totalLength**, maybe they just want a buffer has that length.
So, return a buffer with that length may be better than throw an error.