merge: allow merging going backwards New behavior is generally superior and more correct, except possibly with regards to missing files. hg up . is now effectively a no-op, which is probably the desired behavior for people expecting to move to tip, but may surprise people who were expecting deleted files to reappear. case 1: update to . a-w -> a-w classic: ancestor a missing recreated right? rmed recreated WRONG added forgotten WRONG changed preserved RIGHT conflicted can't happen backward merge: ancestor a (NO EFFECT) missing missing wrong? rm'ed rm'ed RIGHT added preserved RIGHT changed preserved RIGHT conflicted can't happen case 2: update to ancestor of . a-b-w -> b-w \ a classic: ancestor a missing recreated right? rmed recreated wrong? added forgotten wrong? changed preserved RIGHT conflicted preserved wrong? backwards merge: ancestor b missing missing or conflict right? rm'ed missing or conflict right? changed preserved RIGHT conflicted merge RIGHT added preserved right?

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#!/bin/sh

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hg init

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cat > .hg/hgrc <<EOF

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[extensions]

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prefixfilter = prefix.py

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[encode]

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*.txt = stripprefix: Copyright 2046, The Masters

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[decode]

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*.txt = insertprefix: Copyright 2046, The Masters

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EOF

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cat > prefix.py <<EOF

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from mercurial import util

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def stripprefix(s, cmd, filename, **kwargs):

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    header = '%s\n' % cmd

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    if s[:len(header)] != header:

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        raise util.Abort('missing header "%s" in %s' % (cmd, filename))

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    return s[len(header):]

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def insertprefix(s, cmd):

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    return '%s\n%s' % (cmd, s)

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def reposetup(ui, repo):

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    repo.adddatafilter('stripprefix:', stripprefix)

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    repo.adddatafilter('insertprefix:', insertprefix)

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EOF

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cat > .hgignore <<EOF

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.hgignore

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prefix.py

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prefix.pyc

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EOF

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cat > stuff.txt <<EOF

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Copyright 2046, The Masters

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Some stuff to ponder very carefully.

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EOF

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hg add stuff.txt

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hg ci -m stuff

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echo '% Repository data:'

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hg cat stuff.txt

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echo '% Fresh checkout:'

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rm stuff.txt

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hg up -C

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cat stuff.txt

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echo >> stuff.txt <<EOF

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Very very carefully.

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EOF

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hg stat

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cat > morestuff.txt <<EOF

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Unauthorized material subject to destruction.

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EOF

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echo '% Problem encoding:'

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hg add morestuff.txt

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hg ci -m morestuff

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hg stat