#270 broken unit tests

tests/phpunit.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="bootstrap.php">
+<phpunit bootstrap="bootstrap.php" backupGlobals="false">
   <testsuites>
     <testsuite name="AllTests">
       <directory>./units</directory>