py3: use codecs.encode() to encode in rot-13 encoding

The other occurence will need some more love as description is bytes by default
and we need to decode it and then encode it.

Differential Revision: https://phab.mercurial-scm.org/D4608

tests/test-log-exthook.t

@@ -1,60 +1,61
 Test hg log changeset printer external hook
 -------------------------------------------
 
   $ cat > $TESTTMP/logexthook.py <<EOF
   > from __future__ import absolute_import
+  > import codecs
   > from mercurial import (
   >   commands,
   >   logcmdutil,
   >   repair,
   > )
   > def rot13description(self, ctx):
-  >     summary = "summary".encode('rot13')
+  >     summary = codecs.encode("summary", 'rot-13')
   >     description = ctx.description().strip().splitlines()[0].encode('rot13')
   >     self.ui.write("%s:     %s\n" % (summary, description))
   > def reposetup(ui, repo):
   >     logcmdutil.changesetprinter._exthook = rot13description
   > EOF
 
 Prepare the repository
 
   $ hg init empty
   $ cd empty
   $ touch ROOT
   $ hg commit -A -m "Root" ROOT
 
   $ touch a b c
   $ hg commit -A -m "Add A, B, C" a b c
 
 Check the log
 
   $ hg log --config extensions.t=$TESTTMP/logexthook.py
   changeset:   1:70fc82b23320
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   fhzznel:     Nqq N, O, P
   summary:     Add A, B, C
   
   changeset:   0:b00443a54871
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   fhzznel:     Ebbg
   summary:     Root
   
 Check that exthook is working with graph log too
 
   $ hg log -G --config extensions.t=$TESTTMP/logexthook.py
   @  changeset:   1:70fc82b23320
   |  tag:         tip
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  fhzznel:     Nqq N, O, P
   |  summary:     Add A, B, C
   |
   o  changeset:   0:b00443a54871
      user:        test
      date:        Thu Jan 01 00:00:00 1970 +0000
      fhzznel:     Ebbg
      summary:     Root