mercurial/version.py

localrepo.commit: normalize commit message even for rawcommit.

This normalization consists of:
- stripping trailing whitespace
- always using "\n" as the line separator

I think the main reason rawcommit was skipping this normalization was
an attempt to preserve hashes during an hg->hg conversion.

While this is a nice goal, it's not particularly interesting in
practice.  Since SHA-1 is so strong, the only safe way to do it is to
have absolutely identical revisions.  But:

- if the original revision was created with a recent version of hg,
  the commit message will be the same, with or without that
  normalization

- if it was created with an ancient version of hg that didn't do any
  normalization, even if the commit message is identical, the file list
  in the changelog is likely to be different (e.g. no removed files),
  and there were some old issues with e.g. extra file merging, which
  will end up changing the hash anyway

- in any case, if one *really* has to preserve hashes, it's easier
  (and faster) to fake a partial conversion using something like:

  hg clone -U -r rev orig-repo new-repo
  hg -R new-repo log --template '#node# #node#\n' > new-repo/.hg/shamap

Additionally, we've had some reports of problems arising from this lack
of normalization - e.g. issue871, and a user that was wondering why
hg export/hg import was not preserving hashes when there was nothing
unusual going on (it was just import doing the normalization that had
been skipped).

This also means that it's even more unlikely to get identical revisions
when going $VCS->hg->$VCS.

# Copyright (C) 2005, 2006, 2008 by Intevation GmbH
# Author(s):
# Thomas Arendsen Hein <[e-mail]>
#
# This program is free software under the GNU GPL (>=v2)
# Read the file COPYING coming with the software for details.

"""
Mercurial version
"""

import os
import re
import time

unknown_version = 'unknown'
remembered_version = False

def get_version(doreload=False):
    """Return version information if available."""
    try:
        import mercurial.__version__
        if doreload:
            reload(mercurial.__version__)
        version = mercurial.__version__.version
    except ImportError:
        version = unknown_version
    return version

def write_version(version):
    """Overwrite version file."""
    if version == get_version():
        return
    directory = os.path.dirname(__file__)
    for suffix in ['py', 'pyc', 'pyo']:
        try:
            os.unlink(os.path.join(directory, '__version__.%s' % suffix))
        except OSError:
            pass
    f = open(os.path.join(directory, '__version__.py'), 'w')
    f.write("# This file is auto-generated.\n")
    f.write("version = %r\n" % version)
    f.close()
    # reload the file we've just written
    get_version(True)

def remember_version(version=None):
    """Store version information."""
    global remembered_version
    if not version and os.path.isdir(".hg"):
        f = os.popen("hg identify")  # use real hg installation
        ident = f.read()[:-1]
        if not f.close() and ident:
            ids = ident.split(' ', 1)
            version = ids.pop(0)
            if version[-1] == '+':
                version = version[:-1]
                modified = True
            else:
                modified = False
            if version.isalnum() and ids:
                for tag in ids[0].split('/'):
                    # is a tag is suitable as a version number?
                    if re.match(r'^(\d+\.)+[\w.-]+$', tag):
                        version = tag
                        break
            if modified:
                version += time.strftime('+%Y%m%d')
    if version:
        remembered_version = True
        write_version(version)

def forget_version():
    """Remove version information."""
    if remembered_version:
        write_version(unknown_version)