GitHub onebox wrongly adds extra empty lines after each code line in the emails

(Discourse.PRO) #1

An original code (correct rendering):

A email with the code (wrong rendering: extra empty lines are added, the screenshot is taken in the GMail web interface):

(Sam Saffron) #2

Are you sure there are empty lines there and its not simply that the CSS is a bit off?

(Discourse.PRO) #3

The line breaks between the <li> tags are preserved because the code is inside the <pre> tag.
Additionally, each line of code has a bottom padding of 10px:

(Discourse.PRO) #4

Now it became even worse: the violet background now covers only a part of the code block: