Test blank file

lib/linguist/blob_helper.rb

@@ -308,7 +308,7 @@ module Linguist
       # Fail fast if blob isn't viewable?
       return unless viewable?
 
-      if data && (match = lines[0].match(/(.+)\n?/)) && (bang = match[0]) =~ /^#!/
+      if lines.any? && (match = lines[0].match(/(.+)\n?/)) && (bang = match[0]) =~ /^#!/
         bang.sub!(/^#! /, '#!')
         tokens = bang.split(' ')
         pieces = tokens.first.split('/')

test/test_blob.rb

@@ -240,6 +240,7 @@ class TestBlob < Test::Unit::TestCase
     assert_equal Language['VimL'],  blob(".vimrc").language
     assert_equal Language['YAML'],  blob(".gemrc").language
 
+    assert_nil blob("blank").language
     assert_nil blob("README").language
 
     # https://github.com/xquery/xprocxq/blob/master/src/xquery/xproc.xqm