Issues link from project page follows on remote bug tracker if it selected now

app/helpers/issues_helper.rb

@@ -41,6 +41,18 @@ module IssuesHelper
     @project.milestones.active.order("id desc").all
   end
 
+  def url_for_project_issues
+    return "" if @project.nil?
+
+    if @project.used_default_issues_tracker?
+      project_issues_filter_path(@project) 
+    else
+      url = Settings[:issues_tracker][@project.issues_tracker]["project_url"]
+      url.gsub(':project_id', @project.id.to_s)
+         .gsub(':issues_tracker_id', @project.issues_tracker_id.to_s)
+    end
+  end
+
   def url_for_issue(issue_id)
     return "" if @project.nil?
 

app/views/layouts/project_resource.html.haml

@@ -24,8 +24,9 @@
 
         - if @project.issues_enabled 
           = nav_link(controller: %w(issues milestones labels)) do
-            = link_to  project_issues_filter_path(@project)  do
+            = link_to url_for_project_issues do
               Issues
+              - if @project.used_default_issues_tracker?
                 %span.count.issue_counter= @project.issues.opened.count
 
         - if @project.repo_exists? && @project.merge_requests_enabled

config/gitlab.yml.example

@@ -41,6 +41,11 @@ production: &base
   ## External issues trackers
   issues_tracker:
     redmine:
+      ## If not nil, link 'Issues' on project page will be replaced tp this
+      ## Use placeholders:
+      ##  :project_id        - Gitlab project identifier
+      ##  :issues_tracker_id - Project Name or Id in external issue tracker
+      project_url: "http://redmine.sample/projects/:issues_tracker_id"
       ## If not nil, links from /#\d/ entities from commit messages will replaced to this
       ## Use placeholders:
       ##  :project_id        - Gitlab project identifier
@@ -146,6 +151,7 @@ test:
   <<: *base
   issues_tracker:
     redmine:
+      project_url: "http://redmine/projects/:issues_tracker_id"
       issues_url: "http://redmine/:project_id/:issues_tracker_id/:id"
 
 staging: