py3: use absolute_import in printenv.py

tests/printenv.py

@@ -12,6 +12,7 b''
 #   - [output] is the name of the output file (default: use sys.stdout)
 #              the file will be opened in append mode.
 #
+from __future__ import absolute_import
 import os
 import sys
 

tests/test-check-py3-compat.t

@@ -42,7 +42,6 b''
   setup.py not using absolute_import
   tests/heredoctest.py requires print_function
   tests/md5sum.py not using absolute_import
-  tests/printenv.py not using absolute_import
   tests/readlink.py not using absolute_import
   tests/readlink.py requires print_function
   tests/revlog-formatv0.py not using absolute_import