Fix Issue and ExternalIssue reference specs

lib/gitlab/markdown/external_issue_reference_filter.rb

 module Gitlab
   module Markdown
     # HTML filter that replaces external issue tracker references with links.
+    # References are ignored if the project doesn't use an external issue
+    # tracker.
     class ExternalIssueReferenceFilter < ReferenceFilter
       # Public: Find `JIRA-123` issue references in text
       #
@@ -23,6 +25,8 @@ module Gitlab
       ISSUE_PATTERN = /(?<issue>([A-Z\-]+-)\d+)/
 
       def call
+        return doc if project.default_issues_tracker?
+
         replace_text_nodes_matching(ISSUE_PATTERN) do |content|
           issue_link_filter(content)
         end

spec/lib/gitlab/markdown/issue_reference_filter_spec.rb

@@ -16,13 +16,6 @@ module Gitlab::Markdown
         to raise_error(ArgumentError, /:project/)
     end
 
-    it 'ignores valid references when using non-default tracker' do
-      expect(project).to receive(:default_issues_tracker?).and_return(false)
-
-      exp = act = "Issue ##{issue.iid}"
-      expect(filter(act).to_html).to eq exp
-    end
-
     %w(pre code a style).each do |elem|
       it "ignores valid references contained inside '#{elem}' element" do
         exp = act = "<#{elem}>Issue ##{issue.iid}</#{elem}>"
@@ -33,6 +26,13 @@ module Gitlab::Markdown
     context 'internal reference' do
       let(:reference) { "##{issue.iid}" }
 
+      it 'ignores valid references when using non-default tracker' do
+        expect(project).to receive(:issue_exists?).with(issue.iid).and_return(false)
+
+        exp = act = "Issue ##{issue.iid}"
+        expect(filter(act).to_html).to eq exp
+      end
+
       it 'links to a valid reference' do
         doc = filter("See #{reference}")
 
@@ -87,6 +87,14 @@ module Gitlab::Markdown
           to receive(:user_can_reference_project?).and_return(true)
       end
 
+      it 'ignores valid references when cross-reference project uses external tracker' do
+        expect_any_instance_of(Project).to receive(:issue_exists?).
+          with(issue.iid).and_return(false)
+
+        exp = act = "Issue ##{issue.iid}"
+        expect(filter(act).to_html).to eq exp
+      end
+
       it 'links to a valid reference' do
         doc = filter("See #{reference}")