tests: make test-doctest use absolute_import

tests/test-check-py3-compat.t

@@ -55,7 +55,6 b''
   tests/test-atomictempfile.py not using absolute_import
   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-trusted.py requires print_function
 
 #if py3exe

tests/test-doctest.py

@@ -1,8 +1,12 b''
 # this is hack to make sure no escape characters are inserted into the output
-import os, sys
+
+from __future__ import absolute_import
+
+import doctest
+import os
+import sys
 if 'TERM' in os.environ:
     del os.environ['TERM']
-import doctest
 
 def testmod(name, optionflags=0, testtarget=None):
     __import__(name)