MergeRequest#automerge accepts custom message now....

MergeRequest#automerge accepts custom message now. MergeRequest#merge_commit_message generate default one
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/models/merge_request.rb

@@ -214,8 +214,8 @@ class MergeRequest < ActiveRecord::Base
     self.merge
   end
 
-  def automerge!(current_user)
-    if Gitlab::Satellite::MergeAction.new(current_user, self).merge! && self.unmerged_commits.empty?
+  def automerge!(current_user, merge_commit_message = nil)
+    if Gitlab::Satellite::MergeAction.new(current_user, self).merge!(merge_commit_message) && self.unmerged_commits.empty?
       self.merge!(current_user.id)
       true
     end
@@ -319,6 +319,14 @@ class MergeRequest < ActiveRecord::Base
         update_all(updated_at: Time.now)
   end
 
+  def merge_commit_message
+    message = "Merge branch '#{source_branch}' into '#{target_branch}'"
+    message << "\n\n"
+    message << title
+    message << "\n\n"
+    message << description
+  end
+
   private
 
   def dump_commits(commits)