slirp4netns seems to be leaking sockets

[peterboba]

I see a lot of slirp4netns connections in FIN_WAIT2 state:

slirp4netns version 1.3.1
commit: e5e368c4f5db6ae75c2fce786e31eef9da6bf236
libslirp: 4.8.0
SLIRP_CONFIG_VERSION_MAX: 5
libseccomp: 2.5.3

I'm using slirp4netns with rootless containers. I'm wondering whether this is a possible misconfiguration or a bug.
This seems to be easily reproducible when I start netcat to port 443 and send SIGTERM to nc process with kill. slirp4netns connection enters FIN_WAIT2 which is then never cleared.