Merge branch 'fix-post-receive-external-tracker' into 'master'

Fix post-receive errors on a push when an external issue tracker is configured

### What does this MR do?

This MR improves upon !766, fixing errors upon a git push that occur only when an external issue tracker (not JIRA) is used. This MR takes into account that external issue trackers, such as JIRA, may close issues. Disabling the processing of post-receive commits when an external issue tracker is configured seems like the wrong behavior.

### Why was this MR needed?

When a user adds an issue reference, the refactoring in 8f8a8ab and a6defd157 caused `project.get_issue` to be called, causing `ExternalIssue` to be returned when an external issue tracker was configured. This object does not have a `close` method, as needed in `CloseService`. Nor does it make sense to associate a `SystemNote` with this object.

GitLab EE uses a [special case for JIRA](https://gitlab.com/gitlab-org/gitlab-ee/blob/master/app/services/git_push_service.rb#L87). I would recommend moving this logic into `CloseService` too.

### What are the relevant issue numbers?

* Closes #1700
* Closes #1720

See merge request !804

2 files changed, 19 insertions, 0 deletions

diff --git a/spec/services/git_push_service_spec.rb b/spec/services/git_push_service_spec.rb
index e7558f28768..d0941fa2e07 100644
--- a/spec/services/git_push_service_spec.rb
+++ b/spec/services/git_push_service_spec.rb
@@ -233,6 +233,15 @@ describe GitPushService do
 
       expect(Issue.find(issue.id)).to be_opened
     end
+
+    it "doesn't close issues when external issue tracker is in use" do
+      allow(project).to receive(:default_issues_tracker?).and_return(false)
+
+      # The push still shouldn't create cross-reference notes.
+      expect {
+        service.execute(project, user, @oldrev, @newrev, 'refs/heads/hurf')
+      }.not_to change { Note.where(project_id: project.id, system: true).count }
+    end
   end
 
   describe "empty project" do
diff --git a/spec/services/issues/close_service_spec.rb b/spec/services/issues/close_service_spec.rb
index 0e5ae724bf7..db547ce0d50 100644
--- a/spec/services/issues/close_service_spec.rb
+++ b/spec/services/issues/close_service_spec.rb
@@ -31,5 +31,15 @@ describe Issues::CloseService do
         expect(note.note).to include "Status changed to closed"
       end
     end
+
+    context "external issue tracker" do
+      before do
+        allow(project).to receive(:default_issues_tracker?).and_return(false)
+        @issue = Issues::CloseService.new(project, user, {}).execute(issue)
+      end
+
+      it { expect(@issue).to be_valid }
+      it { expect(@issue).to be_opened }
+    end
   end
 end