Modifier.replaceWithFragment doesn't keep block type when fragment has only one content block

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

API Bug:

Passing a fragment with only a ContentBlock that has a type different to unstyled to Modifier.replaceWithFragment the type is lost in the new ContentState

Example in JSFiddle

UAT Bug:

Pasting only an HTML element the block type is not preserved.

Steps to reproduce:

Copy an heading element such as (h1, h2) from any page.
Paste in the demo editor here https://draftjs.org/

What is the expected behavior?

Keep the block type.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?

version: 0.10.5 browser: It's not brower issue, the bug is happening in the helper.

facebookarchive / draft-js

Modifier.replaceWithFragment doesn't keep block type when fragment has only one content block #1868