systemd-sysusers exits with Segmentation fault while creating the tomcat user

When trying to run this manually from /var/lib/dpkg/info/tomcat9.postinst:
systemd-sysusers
Creating group tomcat with gid 998.
Creating user tomcat (Apache Tomcat) with uid 998 and gid 998.
Segmentation fault

We are fairly certain this is related to https://github.com/systemd/systemd/issues/6512

Some groups have lots of members (290+) which can make /etc/gshadow lines long

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OS Info:
Distributor ID: Ubuntu
Description: Ubuntu 18.04.3 LTS
Release: 18.04
Codename: bionic

------------------------------------------------
Package Install:
sudo apt-get install tomcat9
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
  tomcat9-admin tomcat9-docs tomcat9-examples tomcat9-user
Recommended packages:
  libtcnative-1
The following NEW packages will be installed:
  tomcat9
0 upgraded, 1 newly installed, 0 to remove and 20 not upgraded.
Need to get 35.9 kB of archives.
After this operation, 306 kB of additional disk space will be used.
Get:1 http://internal_mirror/bionic-upstream-unstable bionic/main amd64 tomcat9 all 9.0.16-3ubuntu0.18.04.1 [35.9 kB]
Fetched 35.9 kB in 0s (366 kB/s)
Selecting previously unselected package tomcat9.
(Reading database ... 153075 files and directories currently installed.)
Preparing to unpack .../tomcat9_9.0.16-3ubuntu0.18.04.1_all.deb ...
Unpacking tomcat9 (9.0.16-3ubuntu0.18.04.1) ...
Setting up tomcat9 (9.0.16-3ubuntu0.18.04.1) ...
Creating group tomcat with gid 998.
Creating user tomcat (Apache Tomcat) with uid 998 and gid 998.
Segmentation fault
dpkg: error processing package tomcat9 (--configure):
 installed tomcat9 package post-installation script subprocess returned error exit status 139
Errors were encountered while processing:
 tomcat9
E: Sub-process /usr/bin/dpkg returned an error code (1)