OSH spec tests all pass under byterun!

(Unrelated: remove unused 2to3 grammar.  We only care about
py27.grammar.)

opy/README.md

@@ -66,6 +66,11 @@ Gold tests in gold/:

    $ ./test.sh gold

Oil spec tests (slow):

    opy$ ./test.sh spec smoke  # like $REPO_ROOT/test/spec.sh smoke
    opy$ ./test.sh spec all    # like $REPO_ROOT/test/spec.sh all

They can be run manually like this:

    $ gold/regex_compile.py  # run with CPython
@@ -75,11 +80,6 @@ Demo: speed difference between OSH under CPython and OSH under byterun:

    ./demo.sh osh-byterun-speed

TODO:

- Spec tests
  - ./test.sh spec all  # Some failures due to $0

OPy Compiler Regtest
--------------------

opy/test.sh

@@ -161,20 +161,17 @@ unit() {
  PYTHONPATH=. "$@"
}

# NOTE: I checked with set -x that it's being run.  It might be nicer to be
# sure with --verison.

export OSH_PYTHON=opy/_tmp/oil-opy/bin/osh

# NOTE: Failures in 'var-num' and 'special-vars' due to $0.  That proves
# we're running the right binary!
spec() {
  local action=${1:-smoke}
# Spec tests under byterun.
spec() { 
  local action=$1  # e.g. 'smoke' or 'all'
  shift

  pushd ..
  # Could also export OSH_OVM
  test/spec.sh $action "$@"
  pushd $THIS_DIR/..

  # TODO: Should be OSH_ALT instead of OSH_OVM?
  # Usually it is dev build vs. release build, but here it is CPython vs.
  # byterun.
  OSH_OVM=bin/osh-byterun test/spec.sh $action "$@"
  popd
}

test/sh_spec.py

@@ -363,7 +363,7 @@ def CreateAssertions(case, sh_label):
  status = False

  # So the assertion are exactly the same for osh and osh_ALT
  if sh_label == 'osh_ALT':
  if sh_label in ('osh_ALT', 'osh-byterun'):
    sh_label = 'osh'

  if sh_label in case:
@@ -514,7 +514,7 @@ def RunCases(cases, case_predicate, shells, env, out):
      if cell_result == Result.FAIL:
        # Special logic: don't count osh_ALT beacuse its failures will be
        # counted in the delta.
        if sh_label != 'osh_ALT':
        if sh_label not in ('osh_ALT', 'osh-byterun'):
          stats['num_failed'] += 1

        if sh_label == 'osh':
@@ -532,7 +532,7 @@ def RunCases(cases, case_predicate, shells, env, out):
      else:
        raise AssertionError

      if sh_label == 'osh_ALT':
      if sh_label in ('osh_ALT', 'osh-byterun'):
        osh_alt_result = result_row[-1]
        cpython_result = result_row[-2]
        if osh_alt_result != cpython_result: