Do you want to request a feature or report a bug?
This is a bug.

What is the current behavior?
Newlines are added to internal copied text.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. You can use this jsfiddle to get started: https://jsfiddle.net/stopachka/m6z0xn4r/.

This can be reproduced with the 'rich' example:

1. Write some text with an empty newline between blocks. For example:

hello world

foo bar baz

2. Copy and paste all of that text, including the empty newline, into a rich text editor in a separate tab.
3. Notice there are extra newlines in the pasted output, like so:

hello world

foo bar baz

Example:

What is the expected behavior?

There should be only as many newlines as were present in the copied text.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?
This is on the master branch, so 0.10.2+, and I saw it in Chrome, Safari, and Firefox.