Subscriptions: Apostrophe converts to unicode in emails when post is created in Gutenberg

[seejacobscott]

After publishing a post using Gutenberg the subscription email that is sent will convert apostrophes to '

Steps to reproduce the issue:

1. Make sure Jetpack is connected and subscriptions are active
2. Create a post with Gutenberg that includes apostrophes/single-quotes
3. When published, check the email.

What I expected:
Apostrophe/single quote characters to display

What happened instead
' displays in the character's place.

Reported by a user in 778397-zen

Screenshot (from user):

The ticket also contains raw email contents, which also include the ' character.

Seems related to WordPress/gutenberg#3353 (comment)

[gravityrail]

Fixed in r165646-wpcom.

This was occurring because our regex to "autofix" unescaped &'s in URLs was not properly detecting unicode chars of the form &#xNN(NN);

[austinginder]

Thanks so much! Much appreciated.