common and watch options don't play well together

[eggyal]

The documentation for opts.common states:

If using a callback, you're passed an object that with keys of each entry file and values of the compiled JS file.

[ deletia ]

If piping the response you'll [...] need to listen to the 'entry' event to get the compiled entry files.

However, when combined with opts.watch, neither of the above statements are true: subsequent/watchified invocations of the callback receive only a single bundle, and the 'entry' event is not called.

[joeybaker]

Yes, we should do a better job documenting this in the readme. The two options currently are mutually exclusive.