tests/get-with-headers.py

cvsps: use a different tiebreaker to avoid flaky test

After adding some sneaky debug printing[0], I determined that this
test flaked when a CVS commit containing two files starts too close to
the end of a second, thus putting file "a" in one second and "b/c" in
the following second. The secondary sort key meant that these changes
sorted in a different order when the timestamps were different than
they did when they matched. As far as I can tell, CVS walks through
the files in a stable order, so by sorting on the filenames in cvsps
we'll get stable output. It's fine for us to switch from sorting on
the branchpoint as a secondary key because this was already the point
when we didn't care, and we're just trying to break ties in a stable
way. It's unclear to be if having the branchpoint present matters
anymore, but it doesn't really hurt to leave it.

With this change in place, I was able to run test-convert-cvs over 650
times in a row without a failure.  test-convert-cvcs-synthetic.t
appears to still be flaky, but I don't think it's *worse* than it was
before - just not better (I observed one flaky failure in 200 runs on
that test).

0: The helpful debug hack ended up being this, in case it's useful to
future flaky test assassins:

 --- a/hgext/convert/cvsps.py
 +++ b/hgext/convert/cvsps.py
 @@ -854,6 +854,8 @@ def debugcvsps(ui, *args, **opts):
              ui.write(('Branch: %s\n' % (cs.branch or 'HEAD')))
              ui.write(('Tag%s: %s \n' % (['', 's'][len(cs.tags) > 1],
                                    ','.join(cs.tags) or '(none)')))
 +            if cs.comment == 'ci1' and (cs.id == 6) == bool(cs.branchpoints):
 +                ui.write('raw timestamp %r\n' % (cs.date,))
              if cs.branchpoints:
                  ui.write(('Branchpoints: %s \n') %
                           ', '.join(sorted(cs.branchpoints)))

#!/usr/bin/env python

"""This does HTTP GET requests given a host:port and path and returns
a subset of the headers plus the body of the result."""

import httplib, sys

try:
    import msvcrt, os
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

twice = False
if '--twice' in sys.argv:
    sys.argv.remove('--twice')
    twice = True
headeronly = False
if '--headeronly' in sys.argv:
    sys.argv.remove('--headeronly')
    headeronly = True

reasons = {'Not modified': 'Not Modified'} # python 2.4

tag = None
def request(host, path, show):
    assert not path.startswith('/'), path
    global tag
    headers = {}
    if tag:
        headers['If-None-Match'] = tag

    conn = httplib.HTTPConnection(host)
    conn.request("GET", '/' + path, None, headers)
    response = conn.getresponse()
    print response.status, reasons.get(response.reason, response.reason)
    if show[:1] == ['-']:
        show = sorted(h for h, v in response.getheaders()
                      if h.lower() not in show)
    for h in [h.lower() for h in show]:
        if response.getheader(h, None) is not None:
            print "%s: %s" % (h, response.getheader(h))
    if not headeronly:
        print
        data = response.read()
        sys.stdout.write(data)

        if twice and response.getheader('ETag', None):
            tag = response.getheader('ETag')

    return response.status

status = request(sys.argv[1], sys.argv[2], sys.argv[3:])
if twice:
    status = request(sys.argv[1], sys.argv[2], sys.argv[3:])

if 200 <= status <= 305:
    sys.exit(0)
sys.exit(1)