tests/filterpyflakes: use absolute_import

tests/filterpyflakes.py

@@ -2,7 +2,10 b''
 
 # Filter output by pyflakes to control which warnings we check
 
-import sys, re
+from __future__ import absolute_import
+
+import re
+import sys
 
 def makekey(typeandline):
     """

tests/test-check-py3-compat.t

@@ -143,7 +143,6 b''
   mercurial/util.py not using absolute_import
   mercurial/windows.py not using absolute_import
   setup.py not using absolute_import
-  tests/filterpyflakes.py not using absolute_import
   tests/filterpyflakes.py requires print_function
   tests/generate-working-copy-states.py not using absolute_import
   tests/generate-working-copy-states.py requires print_function

tests/test-check-pyflakes.t

@@ -7,6 +7,6 b' run pyflakes on all tracked files ending'
 
   $ hg locate 'set:**.py or grep("^!#.*python")' 2>/dev/null \
   > | xargs pyflakes 2>/dev/null | "$TESTDIR/filterpyflakes.py"
-  tests/filterpyflakes.py:58: undefined name 'undefinedname'
+  tests/filterpyflakes.py:61: undefined name 'undefinedname'