Merge branch 'fix-relative-submodule-namespace-path' into 'master'

Fix Error 500 when relative submodule resolves to a namespace that has a different name from its path

### What does this MR do?

This MR fixes a bug in resolving a namespace when the `name` differed from `path`.

### Why was this MR needed?

The original code was using `name`, when the proper input to `namespace_project_path` was `path`.

### What are the relevant issue numbers?

Closes #1849

See merge request !864

CHANGELOG

@@ -7,6 +7,7 @@ v 7.13.0 (unreleased)
   - Fix error when deleting a user who has projects (Stan Hu)
   - Fix downloading of patches on public merge requests when user logged out (Stan Hu)
   - The password for the default administrator (root) account has been changed from "5iveL!fe" to "password".
+  - Fix Error 500 when relative submodule resolves to a namespace that has a different name from its path (Stan Hu)
   - Update maintenance documentation to explain no need to recompile asssets for omnibus installations (Stan Hu)
   - Support commenting on diffs in side-by-side mode (Stan Hu)
   - Fix JavaScript error when clicking on the comment button on a diff line that has a comment already (Stan Hu)

app/helpers/submodule_helper.rb

@@ -63,7 +63,7 @@ module SubmoduleHelper
     namespace = components.pop.gsub(/^\.\.$/, '')
     if namespace.empty?
-      namespace = @project.namespace.name
+      namespace = @project.namespace.path
     end
     [

spec/helpers/submodule_helper_spec.rb

@@ -115,7 +115,7 @@ describe SubmoduleHelper do
     end
     context 'submodules with relative links' do
-      let(:group) { create(:group) }
+      let(:group) { create(:group, name: "Master Project", path: "master-project") }
       let(:project) { create(:project, group: group) }
       let(:commit_id) { sample_commit[:id] }