newline ignored when using emphasize-lines

[jmd-dk]

Describe the bug

Whenever I use :emphasize-lines: within a .. code-block::, the newline in between the line(s) that is emphasized and the next disappears after copy-paste via sphinx-copybutton 0.5.1. There is no such problem with 0.5.0.

Reproduce the bug

The below simple example shows the bug:

.. code-block::
   :emphasize-lines: 1

   a = 1
   b = 2

The Sphinx generated HTML renders as

a = 1
b = 2

Copying using the copy button and then pasting should preserve this, which is indeed the usual behaviour (e.g. sphinx-copybutton 0.5.0). With sphinx-copybutton 0.5.1 however, pasting results in

a = 1b = 2

List your environment

• sphinx-copybutton 0.5.1
• sphinx 6.1.3
• sphinx-rtd-theme 1.2.0
• Python 3.11.2
• HTML page viewed with Google Chrome 108.0.5359.98
• Linux Mint 20

[jmd-dk]

This is still a problem with sphinx-copybutton 0.5.2.