greylistd does not run after upgrade to 20.04

[Gary Barnes]

After upgrading to Ubuntu 20.04, greylisting stopped working on my mail server.

It seems that the script /usr/sbin/greylistd is not valid python3.

Changing the first line of /usr/sbin/greylistd from #!/usr/bin/python3 to #!/usr/bin/python2 allows me to start greylistd with "sudo service greylistd start", and it seems to function properly, but "sudo service greylistd stop" does not seem to stop greylistd as expected.

1) Description: Ubuntu 20.04 LTS
   Release: 20.04
2) greylistd:
  Installed: 0.8.8.8
  Candidate: 0.8.8.8
  Version table:
 *** 0.8.8.8 500
        500 http://gb.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        500 http://gb.archive.ubuntu.com/ubuntu focal/universe i386 Packages
        100 /var/lib/dpkg/status
3) I expected greylist daemon to run after boot or "sudo service greylistd start"
4) greylist daemon exited immediately after start attempt, probably due to syntax errors.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: greylistd (not installed)
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 27 00:29:37 2020
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: greylistd
UpgradeStatus: Upgraded to focal on 2020-04-25 (1 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.