filemerge: move check for identical sides out of filemerge() `filemerge.filemerge()` returns `None` if no merge was necessary because the two sides were identical. I don't think it should be that function's responsibility to handle that case; we should ideally not even call `filemerge.filemerge()` if the two inputs identical. This patch therefore moves the check out to the caller (`mergestate.py`). The largefiles test changed because we now notice that the two sides made the same change, so we don't consider it a merge. Also note that the new message better matches the line above it in the test output. Differential Revision: https://phab.mercurial-scm.org/D12154

from __future__ import absolute_import, print_function

import sys


def flush():
    sys.stdout.flush()
    sys.stderr.flush()


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:
            flush()
            exec(c, globalvars)
            flush()
        except Exception as inst:
            flush()
            print(repr(inst))