I noticed when I upgraded to IPB 2.3.6, extra linebreaks were left behind when quotes were stripped, after you quote a post containing quotes. I opened a ticket about this, and they pointed me to the sources/classes/post/class_post.php file, which had the linebreak stripping line commented out. I uncommented it, however, that removed ALL linebreaks, which wasn't desired either. Instead, I resolved my issue by leaving that line commented out, and instead inserting the following before the quotestripping line:
$tmp_post = preg_replace( "#(?:\n|\r|\r\n)(\
It effectively removed any extra linebreaks left behind from the quotestripping. You could integrate this into the quotestripping function, but I decided not to because I may want to change the way this is handled on my forum later. Anyways, I just wanted to let you guys be aware of this issue. :)
I didn't post this in the bug section because it's not a bug per se, but I'm suggesting it be added.