Mailman update fails

like this, the update notice came in a few hours ago and fails when applied. Ideas?

D

Now updating mailman …

Installing package(s) with command apt-get -y install mailman ..

Reading package lists...
Building dependency tree...
Reading state information...
Suggested packages:
  mailman3 lynx listadmin
The following packages will be upgraded:
  mailman
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 4352 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://ca.archive.ubuntu.com/ubuntu bionic-security/main amd64 mailman amd64 1:2.1.26-1ubuntu0.3 [4352 kB]
Preconfiguring packages ...
Looking for enabled languages (this may take some time) ... done.
Fetched 4352 kB in 1s (3382 kB/s)
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(Reading database ... 191141 files and directories currently installed.)
Preparing to unpack .../mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb ...
dpkg: error processing archive /var/cache/apt/archives/mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb (--unpack):
 new mailman package pre-installation script subprocess returned error exit status 1
No updates are necessary.
Errors were encountered while processing:
 /var/cache/apt/archives/mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

.. install failed!

No packages were installed. Check the messages above for the cause of the error.

Now updating mailman …

Installing package(s) with command apt-get -y install mailman ..

Reading package lists...
Building dependency tree...
Reading state information...
Suggested packages:
  mailman3 lynx listadmin
The following packages will be upgraded:
  mailman
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 4352 kB of archives.
After this operation, 0 B of additional disk space will be used.
Get:1 http://ca.archive.ubuntu.com/ubuntu bionic-security/main amd64 mailman amd64 1:2.1.26-1ubuntu0.3 [4352 kB]
Preconfiguring packages ...
Looking for enabled languages (this may take some time) ... done.
Fetched 4352 kB in 1s (3382 kB/s)
(Reading database ... 
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading database ... 80%
(Reading database ... 85%
(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 191141 files and directories currently installed.)
Preparing to unpack .../mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb ...
dpkg: error processing archive /var/cache/apt/archives/mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb (--unpack):
 new mailman package pre-installation script subprocess returned error exit status 1
No updates are necessary.
Errors were encountered while processing:
 /var/cache/apt/archives/mailman_1%3a2.1.26-1ubuntu0.3_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

.. install failed!

No packages were installed. Check the messages above for the cause of the error.