convert: add a mode where mercurial_sink skips empty revisions. The getchanges function of some converter_source classes can return some false positives. I.e. they sometimes claim that a file "foo" was changed in some revision, even though its contents are still the same. convert_svn is particularly bad, but I think this can also happen with convert_cvs and, at least in theory, with mercurial_source. For regular conversions this is not really a problem - as long as getfile returns the right contents, we'll get a converted revision with the right contents. But when we use --filemap, this could lead to superfluous revisions being converted. Instead of fixing every converter_source, I decided to change mercurial_sink to work around this problem. When --filemap is used, we're interested only in revisions that touch some specific files. If a revision doesn't change any of these files, then we're not interested in it (at least for revisions with a single parent; merges are special). For mercurial_sink, we abuse this property and rollback a commit if the manifest text hasn't changed. This avoids duplicating the logic from localrepo.filecommit to detect unchanged files.

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#!/usr/bin/env python

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#

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# Based on python's Tools/scripts/md5sum.py

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#

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# This software may be used and distributed according to the terms

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# of the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2, which is

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# GPL-compatible.

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import sys

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import os

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import md5

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for filename in sys.argv[1:]:

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    try:

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        fp = open(filename, 'rb')

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    except IOError, msg:

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        sys.stderr.write('%s: Can\'t open: %s\n' % (filename, msg))

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        sys.exit(1)

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    m = md5.new()

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    try:

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        while 1:

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            data = fp.read(8192)

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            if not data:

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                break

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            m.update(data)

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    except IOError, msg:

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        sys.stderr.write('%s: I/O error: %s\n' % (filename, msg))

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        sys.exit(1)

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    sys.stdout.write('%s  %s\n' % (m.hexdigest(), filename))

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sys.exit(0)