Segfault with scrollback_pager_history_size > 1 and many lines output

[sudoBash418]

Describe the bug
kitty 0.19.0 segfaults after roughly 120k lines with the config option scrollback_pager_history_size set to anything over 1.
This bug does not occur for me on 0.18.3.

To Reproduce
Steps to reproduce the behavior:

1. Use a config file with scrollback_pager_history_size 2
2. Run kitty python -c 'for x in range(10000000): print(x)'
3. See that it segfaults after ~120000 lines printed

Environment details
OS: Arch Linux

Output of kitty --debug-config

kitty 0.19.0 created by Kovid Goyal
Linux hostname 5.8.13-zen1-2-zen #1 ZEN SMP PREEMPT Fri, 02 Oct 2020 15:14:58 +0000 x86_64
Arch Linux \r (\l)
LSB_VERSION=1.4
DISTRIB_ID=Arch
DISTRIB_RELEASE=rolling
DISTRIB_DESCRIPTION="Arch Linux"
Loaded config files: /tmp/tmp-kitty.conf
Running under: X11

Config options different from defaults:
scrollback_pager_history_size 2097152