Munin 2.0: "Date::Manip::Backend" error

Munin as in Debian, currently version 2.0.6, features a noisy error, at least in my servers' Apache error.log:

munin-cgi-graph: Name "Date::Manip::Backend" used only once:
possible typo at /usr/lib/munin/cgi/munin-cgi-graph line 31.

This is due to a bug. It should have been dealt with already (DBTS #561970) but either not sufficiently or something else is going on.

A reasonable workaround is to add no warnings; before line 31 in /usr/lib/munin/cgi/munin-cgi-graph:

BEGIN {
    no warnings;
    $Date::Manip::Backend = 'DM5';
}