removes inconsistency regarding tagging immediately as merged once you create...

removes inconsistency regarding tagging immediately as merged once you create a branch using new branch button and adds changelog entry

CHANGELOG

@@ -119,6 +119,8 @@ v 8.12.1
   - Fix issue with search filter labels not displaying
 
 v 8.12.0
+v 8.12.0 (unreleased)
+  - Removes inconsistency regarding tagging immediatelly as merged once you create a new branch. !6408
   - Update the rouge gem to 2.0.6, which adds highlighting support for JSX, Prometheus, and others. !6251
   - Only check :can_resolve permission if the note is resolvable
   - Bump fog-aws to v0.11.0 to support ap-south-1 region

app/models/repository.rb

@@ -1013,13 +1013,17 @@ class Repository
     branch_commit = commit(branch_name)
     root_ref_commit = commit(root_ref)
 
-    if branch_commit
+    if branch_commit && !same_head?(branch_commit.id, root_ref_commit.id)
       is_ancestor?(branch_commit.id, root_ref_commit.id)
     else
       nil
     end
   end
 
+  def same_head?(first_commit_id, second_commit_id)
+    first_commit_id == second_commit_id
+  end
+
   def merge_base(first_commit_id, second_commit_id)
     first_commit_id = commit(first_commit_id).try(:id) || first_commit_id
     second_commit_id = commit(second_commit_id).try(:id) || second_commit_id