When upgrading from debian koha-common 18.11.03 to 18.11.04, I received the message WARNING: (Bug 21846) You need to manually run /usr/share/koha/intranet/cgi-bin/misc/maintenance/fix_tags_weight.pl to fix possible issues with tags. It seems to me, this should refer to the debian path for that script, which is /usr/share/koha/bin/maintenance/fix_tags_weight.pl
18.11.x is no longer maintained, but something to keep in mind for the future.