contrib/debugcmdserver.py

patch: include flag-only file changes in "special" when filtering (issue5864)

This patch fix the issue5864 (or maybe issue5865 too) which occurs during
split (or I should say at the time of filtering the hunks in interactive
mode) where user hits a not ending loop of "no changes to record".
And it's not only the case for split it will happen in every interactive
case for e.g. `hg commit -i` or `hg uncommit -i`

After looking into code I found that when filtering we have some
notation called "special" for the file headers which doesn't contain
any hunk and just contain the header (for e.g. newly added empty file
or deleted file) where the user cannot change the content of operation.

And I think we can put this "flag-only" file change in that same bucket
of "special". But I doubt a bit about the case when a file have flag change
and atleast one hunk then user won't be able to separate the flag change
from hunks.
Changed test file reflect the fixed behaviour.

Differential Revision: https://phab.mercurial-scm.org/D6058

#!/usr/bin/env python
#
# Dumps output generated by Mercurial's command server in a formatted style to a
# given file or stderr if '-' is specified. Output is also written in its raw
# format to stdout.
#
# $ ./hg serve --cmds pipe | ./contrib/debugcmdserver.py -
# o, 52   -> 'capabilities: getencoding runcommand\nencoding: UTF-8'

from __future__ import absolute_import, print_function
import struct
import sys

if len(sys.argv) != 2:
    print('usage: debugcmdserver.py FILE')
    sys.exit(1)

outputfmt = '>cI'
outputfmtsize = struct.calcsize(outputfmt)

if sys.argv[1] == '-':
    log = sys.stderr
else:
    log = open(sys.argv[1], 'a')

def read(size):
    data = sys.stdin.read(size)
    if not data:
        raise EOFError
    sys.stdout.write(data)
    sys.stdout.flush()
    return data

try:
    while True:
        header = read(outputfmtsize)
        channel, length = struct.unpack(outputfmt, header)
        log.write('%s, %-4d' % (channel, length))
        if channel in 'IL':
            log.write(' -> waiting for input\n')
        else:
            data = read(length)
            log.write(' -> %r\n' % data)
        log.flush()
except EOFError:
    pass
finally:
    if log != sys.stderr:
        log.close()