tests/heredoctest.py

exchange: add "streaming all changes" to bundle2 pulling

This is the beginning of client-side support for performing a stream
clone using bundle2. The main bundle2 pull function checks whether to
perform a streaming clone and outputs a message if so.

While we have a duplicate message, it seems easier to have all the
bundle2 console writing in one location and in an easy-to-read
conditional block.

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))