+ - Socket6 deb: libsocket6-perl
+ rpm: perl-Socket6
+ (pulled in by SpamAssassin and Net::Server,
+ only necessary if using IPv6 with
+ Plack::Middleware::AccessLog or similar
+ on Perl <= 5.12)
+
+ - Crypt::CBC deb: libcrypt-cbc-perl
+ (for the rarely-used PublicInbox::Unsubscribe)