Edit 2: After writing edit 1, the second link (with two empty spaces) turned into non-clickable. So, the text that follows affects the links somehow, but not all of them.
It's not the added text that makes the link unclickable. It's the edit that makes the link unclickable.
Make a post containing a link with two spaces before that. After that, click on "edit" button and save the post without making any edit. You will see that the link becomes unclickable.
The same thing happens when the number of spaces before a link is a multiple of 2.
7 spaces before the link:
https://bitcointalk.org/index.php?board=24.08 spaces before the link:
https://bitcointalk.org/index.php?board=24.0
All the links are not clickable so trying to edit without doing anything will render it not clickable.