py3: use absolute_import in test-filecache.py

tests/test-check-py3-compat.t

@@ -56,7 +56,6 b''
   tests/test-demandimport.py not using absolute_import
   tests/test-demandimport.py requires print_function
   tests/test-doctest.py not using absolute_import
-  tests/test-filecache.py not using absolute_import
   tests/test-filecache.py requires print_function
   tests/test-filelog.py not using absolute_import
   tests/test-filelog.py requires print_function

tests/test-filecache.py

@@ -1,4 +1,7 b''
-import sys, os, subprocess
+from __future__ import absolute_import
+import os
+import subprocess
+import sys
 
 if subprocess.call(['python', '%s/hghave' % os.environ['TESTDIR'],
                     'cacheable']):