Hi, I'm really interested in this topic and I could reproduce this problem in my env.
I'm not sure this workaround is correctly, but I could manage to call extended method 'test_hello' like this;

h2. test_001

<pre><code class="ruby">
# test001/init.rb

require 'test_issues_controller_patch'

Redmine::Plugin.register :test_001 do
name 'Test 001 plugin'
author 'Author name'
description 'This is a plugin for Redmine'
version '0.0.1'
url 'http://example.com/path/to/plugin'
author_url 'http://example.com/about'
end

Rails.configuration.to_prepare do
unless IssuesController.included_modules.include?(TestIssuesControllerPatch)
IssuesController.send :include, TestIssuesControllerPatch # only loaded once at initialized plugin
end
end

# test001/lib/test_issues_controller_patch.rb

module TestIssuesControllerPatch
extend ActiveSupport::Concern
included do
end
end
</code></pre>

h2. test_002

<pre><code class="ruby">
# test_002/init.rb

require 'test_hooks'
require 'test_issues_helper_patch'

Redmine::Plugin.register :test_002 do
name 'Test 002 plugin'
author 'Author name'
description 'This is a plugin for Redmine'
version '0.0.1'
url 'http://example.com/path/to/plugin'
author_url 'http://example.com/about'
end

Rails.configuration.to_prepare do
# do nothing
end

# test_002/lib/test_hook.rb

class TestHooks < Redmine::Hook::ViewListener
def view_issues_show_details_bottom(context={})
context[:hook_caller].instance_eval do
render(:partial => 'test/hello_world')
end
end
end

# test_002/lib/test_issues_helper_patch.rb

module TestIssuesHelperPatch
extend ActiveSupport::Concern
included do
end

def test_hello
'hello world'
end
end

IssuesHelper.send :prepend, TestIssuesHelperPatch # change from include to prepend

# test_002/app/views/test/_hello_world.html.erb

<!-- prevent method missing exception -->
<% if defined?(test_hello) %>
<%= test_hello %>
<% end %>

</code></pre>

As results, test_hello method is appended at the first of method chain.

<pre><code class="ruby">

>> IssuesHelper.instance_methods
[:test_hello, :render_issue_tooltip, :issue_list, :grouped_issue_list, ..... ]

>> IssuesHelper.ancestors
[TestIssuesHelperPatch, IssuesHelper, Redmine::Export::PDF::IssuesPdfHelper, ApplicationHelper, Redmine::Helpers::URL, Redmine::Hook::Helper, Redmine::Themes::Helper, Redmine::SudoMode::Helper, Redmine::Pagination::Helper, GravatarHelper::PublicMethods, Redmine::I18n, Redmine::WikiFormatting::Macros::Definitions]

</code></pre>

Since TestIssueController patch is empty, I'm not sure if the controller patch also works fine.
But I hope to this would be any help and I'm looking forward to any comments, corrections, advise from you and redmine experts.

--------------------------------------------------------------------------------
Found this during investigation on a similar issue.
I could solve this by moving the 'offending' @ControllerPatch@ to @after_initialize@ callback.

For the example here that would mean to simply transform

<pre><code class="ruby">
Rails.configuration.to_prepare do
unless IssuesController.included_modules.include?(TestIssuesControllerPatch)
IssuesController.send :include, TestIssuesControllerPatch # only loaded once at initialized plugin
end
end
</code></pre>

into

<pre><code class="ruby">
Rails.configuration.after_initialize do
unless IssuesController.included_modules.include?(TestIssuesControllerPatch)
IssuesController.send :include, TestIssuesControllerPatch # only loaded once at initialized plugin
end
end
</code></pre>

--------------------------------------------------------------------------------
Hi, Stephan!

The version of Redmine that everyone mainly use will soon be 4.x, then 3.x.
Since I always struggle with plug-in combinations, so your information above is helpful.

Stephan Wiehr wrote:
> Found this during investigation on a similar issue.
> I could solve this by moving the 'offending' @ControllerPatch@ to @after_initialize@ callback.
--------------------------------------------------------------------------------