one-off doveadm commands broken in 2.4.1 when using docker

Hi all

In 2.3, I could use doveadm from the docker image as a standalone tool, but this no longer works in 2.4:

$ docker run --rm -ti dovecot/dovecot:2.3-latest doveadm usage: doveadm [-Dv] [-f <formatter>] <command> [<args>] altmove [-u <user>|-A] [-S <socket_path>] [-r] <search query> [...snip...]

$ docker run --rm -ti dovecot/dovecot:latest-2.4 doveadm doveconf: Fatal: Cannot expand variable %{env:USER_PASSWORD

This was useful for hashing passwords with "doveadm pw". I assume this wasn't an intentional change in how doveadm works. For now I'll just use the old image when hashing passwords.

Thank you! Jean-Luc