hgext/amend.py

errors: move similarity_hint() to error module

I want to be able to reuse it from `UnknownIdentifier`'s constructor.

Moving it results in a new import of `difflib` in the `error`
module. There was a comment at the top of `error.py` saying "Do not
import anything but pycompat here, please", which was added (except
for the "pycompat" bit) in 08cabecfa8a8 (errors: move revlog errors,
2009-01-11). I don't know the reason for the comment. I'm guessing the
point was to not make the module depend on other Mercurial modules. If
that was it, then importing `difflib` should be fine.

Sorry about the churn (I moved this code from the `dispatch` module to
the `scmutil` module very recently).

Differential Revision: https://phab.mercurial-scm.org/D9345

# amend.py - provide the amend command
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""provide the amend command (EXPERIMENTAL)

This extension provides an ``amend`` command that is similar to
``commit --amend`` but does not prompt an editor.
"""

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    cmdutil,
    commands,
    pycompat,
    registrar,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

cmdtable = {}
command = registrar.command(cmdtable)


@command(
    b'amend',
    [
        (
            b'A',
            b'addremove',
            None,
            _(b'mark new/missing files as added/removed before committing'),
        ),
        (b'e', b'edit', None, _(b'invoke editor on commit messages')),
        (b'i', b'interactive', None, _(b'use interactive mode')),
        (
            b'',
            b'close-branch',
            None,
            _(b'mark a branch as closed, hiding it from the branch list'),
        ),
        (b's', b'secret', None, _(b'use the secret phase for committing')),
        (b'n', b'note', b'', _(b'store a note on the amend')),
    ]
    + cmdutil.walkopts
    + cmdutil.commitopts
    + cmdutil.commitopts2
    + cmdutil.commitopts3,
    _(b'[OPTION]... [FILE]...'),
    helpcategory=command.CATEGORY_COMMITTING,
    inferrepo=True,
)
def amend(ui, repo, *pats, **opts):
    """amend the working copy parent with all or specified outstanding changes

    Similar to :hg:`commit --amend`, but reuse the commit message without
    invoking editor, unless ``--edit`` was set.

    See :hg:`help commit` for more details.
    """
    opts = pycompat.byteskwargs(opts)
    cmdutil.checknotesize(ui, opts)

    with repo.wlock(), repo.lock():
        if not opts.get(b'logfile'):
            opts[b'message'] = opts.get(b'message') or repo[b'.'].description()
        opts[b'amend'] = True
        return commands._docommit(ui, repo, *pats, **pycompat.strkwargs(opts))