py3: use absolute_import in test-propertycache.py

tests/test-check-py3-compat.t

@@ -62,7 +62,6 b''
   tests/test-manifest.py not using absolute_import
   tests/test-pathencode.py not using absolute_import
   tests/test-pathencode.py requires print_function
-  tests/test-propertycache.py not using absolute_import
   tests/test-propertycache.py requires print_function
   tests/test-revlog-ancestry.py not using absolute_import
   tests/test-revlog-ancestry.py requires print_function

tests/test-propertycache.py

@@ -4,7 +4,9 b' The repoview overlay is quite complex. W'
 property cache of both localrepo and repoview to prevent
 regression."""
 
-import os, subprocess
+from __future__ import absolute_import
+import os
+import subprocess
 import mercurial.localrepo
 import mercurial.repoview
 import mercurial.util