Merge branch '20708-new-branch-is-immediatelly-tagged-as-merged' into 'master'

Removes inconsistency regarding tagging immediately as merged once you create a …

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?


Closes #20708

See merge request !6408

1 files changed, 2 insertions, 1 deletions

diff --git a/app/models/repository.rb b/app/models/repository.rb
index 4da1933c189..608c99eed46 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -1016,7 +1016,8 @@ class Repository
     root_ref_commit = commit(root_ref)
 
     if branch_commit
-      is_ancestor?(branch_commit.id, root_ref_commit.id)
+      same_head = branch_commit.id == root_ref_commit.id
+      !same_head && is_ancestor?(branch_commit.id, root_ref_commit.id)
     else
       nil
     end