Twitter auto embedding breaks if user name starts and ends with an underscore

[edent]

1. Try to embed a Tweet where the user's name starts and ends with _
2. For example https://twitter.com/_sagesharp_/status/1061094348152918017
3. The text is rendered as https://twitter.com/<em>sagesharp</em>/status/1061094348152918017 rather than an oembed.
4. The JetPack MarkDown processor is incorrectly interpreting the underscores in a URL as being valid MarkDown.

Tried on a fresh install of 4.9.8, with only JetPack installed, MarkDown editing switched on, and using the classic editor.

This works fine for embedding [tweet 1061094348152918017]

[edent]

Incorrectly rendered tweet

[edent]

MarkDown editing

[swissspidy]

Hi there and welcome to WordPress Trac!

You mentioned that you use Jetpack and that its Markdown processing incorrectly handles the Twitter URL.

Jetpack is a WordPress plugin developed by Automattic and is not part of WordPress core or anything. That means you have to report this issue directly to them as it's not caused by WordPress.

[edent]

Thanks. Raised as ​https://github.com/Automattic/jetpack/issues/10595