tests/test-check-commit.t

run-tests: fix `HGTESTEXTRAEXTENSIONS` with py3

Since `extensions` was a str and `section` bytes, it never populated anything.
If it had, it would have put bytes into the environment dictionary that is all
str.  As everything starts and ends as str, remove the incomplete attempt at
byteification.  It doesn't appear that we had any test coverage of this bit of
code, so also add a non-extension config to make sure it is filtered out
properly.

Differential Revision: https://phab.mercurial-scm.org/D9557

#require test-repo

Enable obsolescence to avoid the warning issue when obsmarker are found

  $ . "$TESTDIR/helpers-testrepo.sh"

Go back in the hg repo

  $ cd $TESTDIR/..

  $ REVSET='not public() and ::. and not desc("# no-check-commit")'

  $ mkdir "$TESTTMP/p"
  $ REVS=`testrepohg log -r "$REVSET" -T.`
  $ if [ -n "$REVS" ] ; then
  >   testrepohg export --git -o "$TESTTMP/p/%n-%h" -r "$REVSET"
  >   for f in `ls "$TESTTMP/p"`; do
  >      contrib/check-commit < "$TESTTMP/p/$f" > "$TESTTMP/check-commit.out"
  >      if [ $? -ne 0 ]; then
  >          node="${f##*-}"
  >          echo "Revision $node does not comply with rules"
  >          echo '------------------------------------------------------'
  >          cat ${TESTTMP}/check-commit.out
  >          echo
  >     fi
  >   done
  > fi