showstack: use absolute_import

contrib/showstack.py

@@ -2,7 +2,10
 #
 # binds to both SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)
 
-import sys, signal, traceback
+from __future__ import absolute_import
+import signal
+import sys
+import traceback
 
 def sigshow(*args):
     sys.stderr.write("\n")

tests/test-check-py3-compat.t

@@ -9,7 +9,6
   contrib/python-hook-examples.py not using absolute_import
   contrib/revsetbenchmarks.py not using absolute_import
   contrib/revsetbenchmarks.py requires print_function
-  contrib/showstack.py not using absolute_import
   contrib/synthrepo.py not using absolute_import
   doc/check-seclevel.py not using absolute_import
   doc/gendoc.py not using absolute_import