Strip trailing whitespace in relative submodule URL

app/helpers/submodule_helper.rb

@@ -73,6 +73,7 @@ module SubmoduleHelper
   end
 
   def relative_self_links(url, commit)
+    url.rstrip!
     # Map relative links to a namespace and project
     # For example:
     # ../bar.git -> same namespace, repo bar

changelogs/unreleased/dm-relative-submodule-url-trailing-whitespace.yml

+---
+title: Strip trailing whitespace in relative submodule URL
+merge_request:
+author:

spec/helpers/submodule_helper_spec.rb

@@ -170,6 +170,11 @@ describe SubmoduleHelper do
         expect(result).to eq(["/#{group.path}/test", "/#{group.path}/test/tree/#{commit_id}"])
       end
 
+      it 'with trailing whitespace' do
+        result = relative_self_links('../test.git ', commit_id)
+        expect(result).to eq(["/#{group.path}/test", "/#{group.path}/test/tree/#{commit_id}"])
+      end
+
       it 'two levels down' do
         result = relative_self_links('../../test.git', commit_id)
         expect(result).to eq(["/#{group.path}/test", "/#{group.path}/test/tree/#{commit_id}"])