Don't modify "match" diff lines. #3945

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/gitlab/diff/highlight.rb b/lib/gitlab/diff/highlight.rb
index 40a54ede2bb..c780ea21775 100644
--- a/lib/gitlab/diff/highlight.rb
+++ b/lib/gitlab/diff/highlight.rb
@@ -25,7 +25,12 @@ module Gitlab
 
       def update_diff_lines
         @highlighted_code.lines.each_with_index do |line, i|
-          @diff_lines[i].text = "#{@diff_line_prefixes[i]}#{line}"
+          diff_line = @diff_lines[i]
+
+          # ignore highlighting for "match" lines
+          next if diff_line.type == 'match'
+
+          diff_line.text = "#{@diff_line_prefixes[i]}#{line}"
         end
 
         @diff_lines