Fix jira integration for EE

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/models/project.rb

@@ -752,4 +752,12 @@ class Project < ActiveRecord::Base
     errors.add(:base, 'Failed create wiki')
     false
   end
+
+  def reference_issue_tracker?
+    default_issues_tracker? || jira_tracker_active?
+  end
+
+  def jira_tracker_active?
+    jira_tracker? && jira_service.active
+  end
 end

app/services/git_push_service.rb

@@ -92,7 +92,7 @@ class GitPushService
         end
       end
 
-      if project.default_issues_tracker?
+      if project.reference_issue_tracker?
         create_cross_reference_notes(commit, issues_to_close)
       end
     end

app/services/system_note_service.rb

@@ -224,7 +224,7 @@ class SystemNoteService
   #
   # Returns Boolean
   def self.cross_reference_disallowed?(noteable, mentioner)
-    return true if noteable.is_a?(ExternalIssue)
+    return true if noteable.is_a?(ExternalIssue) && !noteable.project.jira_tracker_active?
     return false unless mentioner.is_a?(MergeRequest)
     return false unless noteable.is_a?(Commit)