Fix bug causing @whatever inside code blocks to sometimes be picked up as a user mention.

CHANGELOG

@@ -3,7 +3,8 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 7.11.0 (unreleased)
   - Fix clone URL field and X11 Primary selection (Dmitry Medvinsky)
   - Ignore invalid lines in .gitmodules
-  -
+  - Fix bug causing `@whatever` inside an issue's first code block to be picked up as a user mention.
+  - Fix bug causing `@whatever` inside an inline code snippet (backtick-style) to be picked up as a user mention.
   -
   -
   -

app/models/concerns/mentionable.rb

@@ -28,7 +28,7 @@ module Mentionable
 
   # Construct a String that contains possible GFM references.
   def mentionable_text
-    self.class.mentionable_attrs.map { |attr| send(attr) || '' }.join
+    self.class.mentionable_attrs.map { |attr| send(attr) }.compact.join("\n\n")
   end
 
   # The GFM reference to this Mentionable, which shouldn't be included in its #references.

lib/gitlab/reference_extractor.rb

@@ -18,8 +18,8 @@ module Gitlab
       text = text.dup
 
       # Remove preformatted/code blocks so that references are not included
-      text.gsub!(%r{<pre>.*?</pre>|<code>.*?</code>}m) { |match| '' }
-      text.gsub!(%r{^```.*?^```}m) { |match| '' }
+      text.gsub!(/^```.*?^```/m, '')
+      text.gsub!(/[^`]`[^`]*?`[^`]/, '')
 
       @references = Hash.new { |hash, type| hash[type] = [] }
       parse_references(text)