py3: whitelist more passing tests

I had some good success tonight with histedit
tests. test-histedit-fold.t is now low-hanging fruit: it is only
failing because the logic for setting environment variables in hook.py
is slightly busted. Specifically, hook.py line 142 should be making
sure it puts strings in the env dict, not bytes, to avoid b'' goo in
environment variables.

Differential Revision: https://phab.mercurial-scm.org/D2249

contrib/python3-whitelist

@@ -90,11 +90,15 b' test-generaldelta.t'
 test-glog-topological.t
 test-gpg.t
 test-hghave.t
+test-histedit-arguments.t
+test-histedit-base.t
 test-histedit-bookmark-motion.t
 test-histedit-commute.t
 test-histedit-drop.t
 test-histedit-edit.t
+test-histedit-fold-non-commute.t
 test-histedit-no-change.t
+test-histedit-non-commute.t
 test-histedit-obsolete.t
 test-histedit-outgoing.t
 test-http-clone-r.t