tests/heredoctest.py

py3: replace file() with open() in test-convert-mtn.t

While I was here, I added b'' prefixes to make sure we write things correctly in
bytes mode on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D2111

from __future__ import absolute_import, print_function

import sys

globalvars = {}
lines = sys.stdin.readlines()
while lines:
    l = lines.pop(0)
    if l.startswith('SALT'):
        print(l[:-1])
    elif l.startswith('>>> '):
        snippet = l[4:]
        while lines and lines[0].startswith('... '):
            l = lines.pop(0)
            snippet += l[4:]
        c = compile(snippet, '<heredoc>', 'single')
        try:
            exec(c, globalvars)
        except Exception as inst:
            print(repr(inst))