Fallback to current user when suggesting approvers

A new MR won't have an author necessarily, so use the current user in
that case.

app/controllers/projects/merge_requests_controller.rb

@@ -707,7 +707,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   def set_suggested_approvers
     if @merge_request.requires_approve?
       @suggested_approvers = Gitlab::AuthorityAnalyzer.new(
-        @merge_request
+        @merge_request,
+        @merge_request.author || current_user
       ).calculate(@merge_request.approvals_required)
     end
   end

lib/gitlab/authority_analyzer.rb

@@ -2,8 +2,9 @@ module Gitlab
   class AuthorityAnalyzer
     COMMITS_TO_CONSIDER = 25
 
-    def initialize(merge_request)
+    def initialize(merge_request, skip_user)
       @merge_request = merge_request
+      @skip_user = skip_user
       @users = Hash.new(0)
     end
 
@@ -20,7 +21,7 @@ module Gitlab
       @repo = @merge_request.target_project.repository
 
       @repo.commits(@merge_request.target_branch, path: list_of_involved_files, limit: COMMITS_TO_CONSIDER).each do |commit|
-        if commit.author && commit.author != @merge_request.author
+        if commit.author && commit.author != @skip_user
           @users[commit.author] += 1
         end
       end

spec/lib/gitlab/authority_analyzer_spec.rb

@@ -6,7 +6,7 @@ describe Gitlab::AuthorityAnalyzer, lib: true do
     let(:author) { create(:user) }
     let(:user_a) { create(:user) }
     let(:user_b) { create(:user) }
-    let(:merge_request) { create(:merge_request, target_project: project, source_project: project, author: author) }
+    let(:merge_request) { create(:merge_request, target_project: project, source_project: project) }
     let(:files) { [double(:file, deleted_file: true, old_path: 'foo')] }
 
     let(:commits) do
@@ -19,7 +19,7 @@ describe Gitlab::AuthorityAnalyzer, lib: true do
       ]
     end
 
-    let(:approvers) { Gitlab::AuthorityAnalyzer.new(merge_request).calculate(number_of_approvers) }
+    let(:approvers) { Gitlab::AuthorityAnalyzer.new(merge_request, author).calculate(number_of_approvers) }
 
     before do
       merge_request.compare = double(:compare, raw_diffs: files)