Merge branch 'truncate-fix' into 'master'

Fix truncate_first_line if message is nil

Fixes https://gitlab.com/gitlab-org/gitlab-ci/issues/255

/cc @jacobvosmaer 

See merge request !217

app/helpers/commits_helper.rb

@@ -17,6 +17,6 @@ module CommitsHelper
   end
   def truncate_first_line(message, length = 50)
-    truncate(message.lines.first.chomp, length: length)
+    truncate(message.each_line.first.chomp, length: length) if message
   end
 end