[PATCH 3 of 5 stable] contrib: remove one test from the python 3 whitelist

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1500925077 14400
#      Mon Jul 24 15:37:57 2017 -0400
# Branch stable
# Node ID 5af4fa0a0bbbeadb3569b68f0440120a786c81f2
# Parent  50d37101218f32625d36b632e25e52f588e8d925
contrib: remove one test from the python 3 whitelist

439b4d005b4a introduced a use of 'hg revert --no-backup' which is
currently broken. Rather than try and do a fix on the (complicated)
revert code during the freeze, let's just give up on this test under
Python 3 until later. Once we do fix things, the test ratchet script
will re-enable it.

diff --git a/contrib/python3-whitelist b/contrib/python3-whitelist
--- a/contrib/python3-whitelist
+++ b/contrib/python3-whitelist
@@ -24,7 +24,6 @@ test-locate.t
 test-lrucachedict.py
 test-manifest.py
 test-merge-default.t
-test-merge-subrepos.t
 test-merge2.t
 test-merge5.t
 test-revlog-packentry.t