MRs author can cancel automatic merge

app/controllers/projects/merge_requests_controller.rb

@@ -150,7 +150,9 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   end
   def cancel_merge_when_build_succeeds
-    return access_denied! unless @merge_request.can_be_merged_by?(current_user)
+    unless @merge_request.can_be_merged_by?(current_user) || @merge_request.author == current_user
+      return access_denied!
+    end
     if @merge_request.merge_when_build_succeeds?
       @merge_request.reset_merge_when_build_succeeds

app/views/projects/merge_requests/widget/open/_merge_when_build_succeeds.html.haml

@@ -14,7 +14,7 @@
       = succeed '.' do
         The changes will be merged into
         %span.label-branch= @merge_request.target_branch
-      The source branch will not be removed.
+      The source branch won't be removed.
 - if remove_source_branch_button || @merge_request.can_be_merged_by?(current_user)
   .clearfix.prepend-top-10
@@ -22,6 +22,6 @@
       = link_to merge_namespace_project_merge_request_path(@merge_request.source_project.namespace, @merge_request.source_project, @merge_request, merge_when_build_succeeds: true, should_remove_source_branch: true), remote: true, method: :post, class: "btn btn-grouped btn-primary btn-sm remove_source_branch" do
         = icon('times')
         Remove Source Branch When Merged
-    - if @merge_request.can_be_merged_by?(current_user)
+    - if @merge_request.can_be_merged_by?(current_user) || @merge_request.author == current_user
       = link_to merge_namespace_project_merge_request_path(@merge_request.source_project.namespace, @merge_request.source_project, @merge_request), remote: true, method: :delete, class: "btn btn-grouped btn-warning btn-sm" do
         Cancel Automatic Merge