Merge branch 'mr-commit-comment-diff-lines' into 'master'

Fix commit comments on first line of diff not rendering in Merge Request Discussion view.

Example can be seen near the bottom on this MR: !1533.

Before:

![Screen Shot 2015-02-20 at 10.24.34](https://dev.gitlab.org/uploads/gitlab/gitlabhq/35600b98b5/Screen_Shot_2015-02-20_at_10.24.34.png)

After: the [note](https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1533/diffs#note_36449) is actually rendered.

See merge request !1552

CHANGELOG

 v 7.9.0 (unreleased)
   - Move labels/milestones tabs to sidebar
   - Improve UI for commits, issues and merge request lists
+  - Fix commit comments on first line of diff not rendering in Merge Request Discussion view.
 
 v 7.8.0 (unreleased)
   - Fix access control and protection against XSS for note attachments and other uploads.

app/models/note.rb

@@ -409,19 +409,19 @@ class Note < ActiveRecord::Base
     prev_lines = []
 
     diff_lines.each do |line|
-      if generate_line_code(line) != self.line_code
-        if line.type == "match"
-          prev_lines.clear
-          prev_match_line = line
-        else
-          prev_lines.push(line)
-          prev_lines.shift if prev_lines.length >= max_number_of_lines
-        end
+      if line.type == "match"
+        prev_lines.clear
+        prev_match_line = line
       else
         prev_lines << line
-        return prev_lines
+        
+        break if generate_line_code(line) == self.line_code
+
+        prev_lines.shift if prev_lines.length >= max_number_of_lines
       end
     end
+
+    prev_lines
   end
 
   def diff_lines

lib/gitlab/diff/parser.rb

@@ -27,7 +27,7 @@ module Gitlab
             line_old = line.match(/\-[0-9]*/)[0].to_i.abs rescue 0
             line_new = line.match(/\+[0-9]*/)[0].to_i.abs rescue 0
 
-            next if line_old == 1 && line_new == 1 #top of file
+            next if line_old <= 1 && line_new <= 1 #top of file
             lines_obj << Gitlab::Diff::Line.new(full_line, type, line_obj_index, line_old, line_new)
             line_obj_index += 1
             next