Sorry for replying late (I completely missed the notification).

My use-case was recording on IRC level into files, and rotating the raw-logs from inside irssi.
I had issues that the new logfile ends up having duplicates of the buffer, so i basically wanted to set the buffer to a single line.
I did play around for a bit (mainly in the config files), but couldn't get it smaller.
(There might be ways to do this without that code change, but as I already modified the log-format for my purpose, I just also added the ability to shrink)

I primarily raised the pull request because the behavior of: only ever removing one item after adding one and therefore never being able to shrink the buffer, "felt" a bit wrong. And removing items in a loop as long as the buffer is larger than it's maximum seemed a bit more straight-forward to me.

I don't have a strong opinion about this, as the change is kinda cosmetic, therefore I don't have any issue if it get's rejected.