Merge pull request #1940 from github/fix-multiple-extensions

Fix for extensions with multiple segments

lib/linguist/language.rb

@@ -548,7 +548,7 @@ module Linguist
 
     if extnames = extensions[name]
       extnames.each do |extname|
-        if !options['extensions'].include?(extname)
+        if !options['extensions'].index { |x| x.end_with? extname }
           warn "#{name} has a sample with extension (#{extname}) that isn't explicitly defined in languages.yml" unless extname == '.script!'
           options['extensions'] << extname
         end