Lintian warning: groff-message <manpage> can't set the locale; make sure $LC_* and $LANG are correct

For some days I observe the lintian warning

groff-message manpage can't set the locale; make sure $LC_* and $LANG are correct

in nearly all of my packages, which are all checked every week.

As an example you can have a look at https://salsa.debian.org/perl-team/modules/packages/libcrypt-des-perl:

Job #1105190 at 2020-10-25 06:25 triggers the warning:

W: libcrypt-des-perl: groff-message usr/share/man/man3/Crypt::DES.3pm.gz can't set the locale; make sure $LC_* and $LANG are correct

while Job #1082839 at 2020-10-18 07:22 did not trigger the warning.

Okay, Lintian was upgraded from 2.98 to 2.99 in between, but lintian changelog doesn't mention changes in this section.

On my own system I cannot reproduce the warning with lintian 2.99, so I think that the problem exists in the lintian docker image, that runs the salsa lintian check, where no UTF-8 locale may be installed.