Redmine

I have redmine 4.1.1 installed with additionals plugin 3.0.1. When I installed the additional_tags plugin, I got an error for an undefined method "additionals_settings_select". Sure enough, it is missing from the additionals plugin helper, in plugins/additionals/app/helpers/additionals_settings_helper.rb.

If I go to a temp directory and clone additionals:

cd ~/tmp
mkdir additionals
git clone https://www.github.com/alphanodes/additionals.git

I get an up-to-date copy which includes the missing method.
This is on branch origin/master.

When I cd'd to the redmine/plugins/additionals directory and did a git pull, it updated but the files are different, and the method is still missing.

$ git status
On branch stable
Your branch is up to date with 'origin/stable'.

The clone is on branch master, so apparently the stable branch is missing the needed methods.

The additional_tags plugin is version 1.0.0, and additionals is 3.0.1.
What is the best way to proceed?

This seems like a bug but I don't know how to file bugs on plugins and maybe I've just got something messed up.

Environment:
  Redmine version                4.1.1.stable
  Ruby version                   2.6.6-p146 (2020-03-31) [x86_64-linux]
  Rails version                  5.2.4.2
  Environment                    redmine_test
  Database adapter               Mysql2
  Mailer queue                   ActiveJob::QueueAdapters::AsyncAdapter
  Mailer delivery                sendmail
SCM:
  Git                            2.17.1
  Filesystem                     
Redmine plugins:
  additional_tags                1.0.0
  additionals                    3.0.1
  redmine_omniauth_google        0.0.1

Running on GCE ubuntu 18.04.1