Backport 'Rebase' feature from EE to CEjprovazn-rebase

When a project uses fast-forward merging strategy user has
to rebase MRs to target branch before it can be merged.
Now user can do rebase in UI by clicking 'Rebase' button
instead of doing rebase locally.

This feature was already present in EE, this is only backport
of the feature to CE. Couple of changes:
* removed rebase license check
* renamed migration (changed timestamp)

Closes #40301

1 files changed, 18 insertions, 0 deletions

diff --git a/app/presenters/merge_request_presenter.rb b/app/presenters/merge_request_presenter.rb
index ab4c87c0169..c6806b7cc26 100644
--- a/app/presenters/merge_request_presenter.rb
+++ b/app/presenters/merge_request_presenter.rb
@@ -76,6 +76,12 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
     end
   end
 
+  def rebase_path
+    if !rebase_in_progress? && should_be_rebased? && user_can_push_to_source_branch?
+      rebase_project_merge_request_path(project, merge_request)
+    end
+  end
+
   def target_branch_tree_path
     if target_branch_exists?
       project_tree_path(project, target_branch)
@@ -152,6 +158,10 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
     user_can_collaborate_with_project? && can_be_cherry_picked?
   end
 
+  def can_push_to_source_branch?
+    source_branch_exists? && user_can_push_to_source_branch?
+  end
+
   private
 
   def conflicts
@@ -174,6 +184,14 @@ class MergeRequestPresenter < Gitlab::View::Presenter::Delegated
     end.sort.to_sentence
   end
 
+  def user_can_push_to_source_branch?
+    return false unless source_branch_exists?
+
+    ::Gitlab::UserAccess
+      .new(current_user, project: source_project)
+      .can_push_to_branch?(source_branch)
+  end
+
   def user_can_collaborate_with_project?
     can?(current_user, :push_code, project) ||
       (current_user && current_user.already_forked?(project))