Pressing enter twice creates a single line break in the published post

[rachelmcr]

Expected behavior

Pressing enter should display a paragraph break. Pressing enter twice should display two paragraph breaks, and the published post should either add a non-breaking space in each new paragraph (to preserve those extra paragraph breaks — this is the Calypso web editor behavior) or remove any extra paragraphs with no text.

Actual behavior

Pressing enter twice displays two paragraph breaks, but after publishing or updating the post the space is collapsed into a single line break.

Screenshots

Pressing enter twice:

After tapping Update on the post:

Tested on iPhone 6, iOS 9.3.2, WPiOS 6.4.0.20160707.1

Related issue for Android: wordpress-mobile/WordPress-Editor-Android#438