histedit: simplify computation of `newchildren` during --continue

We are now checking for any changesets between the previous `parentctx` and the
current working directory parent. If the current working directory parent is
inconsistent, we abort.

This change is useful as it simplifies the --continue process, easing upcoming
changes.

While working on this changeset, I spotted an unhandled corner case. This corner
case is now documented and have an appropriate issue in the tracker (issue3655).
However, the corner case is still unhandled. handling this test case would
required some additional work:

- actually decide what the proper behavior should be:
- change content of "histedit-state" to add missing data necessary to detect
  the situation
- add proper testcase,

But leaving the case unhandled is "okay":

- this is not a regression,
- this is not the purpose of the current series,
- the freeze was near and I had more critical stuff to attend to,
- this is a simple but non trivial, (see above)

hgext/histedit.py

@@ -1,743 +1,742 b''
 # histedit.py - interactive history editing for mercurial
 #
 # Copyright 2009 Augie Fackler <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 """interactive history editing
 
 With this extension installed, Mercurial gains one new command: histedit. Usage
 is as follows, assuming the following history::
 
  @  3[tip]   7c2fd3b9020c   2009-04-27 18:04 -0500   durin42
  |    Add delta
  |
  o  2   030b686bedc4   2009-04-27 18:04 -0500   durin42
  |    Add gamma
  |
  o  1   c561b4e977df   2009-04-27 18:04 -0500   durin42
  |    Add beta
  |
  o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
       Add alpha
 
 If you were to run ``hg histedit c561b4e977df``, you would see the following
 file open in your editor::
 
  pick c561b4e977df Add beta
  pick 030b686bedc4 Add gamma
  pick 7c2fd3b9020c Add delta
 
  # Edit history between 633536316234 and 7c2fd3b9020c
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but fold into previous commit (combines N and N-1)
  #  d, drop = remove commit from history
  #  m, mess = edit message without changing commit content
  #
 
 In this file, lines beginning with ``#`` are ignored. You must specify a rule
 for each revision in your history. For example, if you had meant to add gamma
 before beta, and then wanted to add delta in the same revision as beta, you
 would reorganize the file to look like this::
 
  pick 030b686bedc4 Add gamma
  pick c561b4e977df Add beta
  fold 7c2fd3b9020c Add delta
 
  # Edit history between 633536316234 and 7c2fd3b9020c
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but fold into previous commit (combines N and N-1)
  #  d, drop = remove commit from history
  #  m, mess = edit message without changing commit content
  #
 
 At which point you close the editor and ``histedit`` starts working. When you
 specify a ``fold`` operation, ``histedit`` will open an editor when it folds
 those revisions together, offering you a chance to clean up the commit message::
 
  Add beta
  ***
  Add delta
 
 Edit the commit message to your liking, then close the editor. For
 this example, let's assume that the commit message was changed to
 ``Add beta and delta.`` After histedit has run and had a chance to
 remove any old or temporary revisions it needed, the history looks
 like this::
 
  @  2[tip]   989b4d060121   2009-04-27 18:04 -0500   durin42
  |    Add beta and delta.
  |
  o  1   081603921c3f   2009-04-27 18:04 -0500   durin42
  |    Add gamma
  |
  o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
       Add alpha
 
 Note that ``histedit`` does *not* remove any revisions (even its own temporary
 ones) until after it has completed all the editing operations, so it will
 probably perform several strip operations when it's done. For the above example,
 it had to run strip twice. Strip can be slow depending on a variety of factors,
 so you might need to be a little patient. You can choose to keep the original
 revisions by passing the ``--keep`` flag.
 
 The ``edit`` operation will drop you back to a command prompt,
 allowing you to edit files freely, or even use ``hg record`` to commit
 some changes as a separate commit. When you're done, any remaining
 uncommitted changes will be committed as well. When done, run ``hg
 histedit --continue`` to finish this step. You'll be prompted for a
 new commit message, but the default commit message will be the
 original message for the ``edit`` ed revision.
 
 The ``message`` operation will give you a chance to revise a commit
 message without changing the contents. It's a shortcut for doing
 ``edit`` immediately followed by `hg histedit --continue``.
 
 If ``histedit`` encounters a conflict when moving a revision (while
 handling ``pick`` or ``fold``), it'll stop in a similar manner to
 ``edit`` with the difference that it won't prompt you for a commit
 message when done. If you decide at this point that you don't like how
 much work it will be to rearrange history, or that you made a mistake,
 you can use ``hg histedit --abort`` to abandon the new changes you
 have made and return to the state before you attempted to edit your
 history.
 
 If we clone the example repository above and add three more changes, such that
 we have the following history::
 
    @  6[tip]   038383181893   2009-04-27 18:04 -0500   stefan
    |    Add theta
    |
    o  5   140988835471   2009-04-27 18:04 -0500   stefan
    |    Add eta
    |
    o  4   122930637314   2009-04-27 18:04 -0500   stefan
    |    Add zeta
    |
    o  3   836302820282   2009-04-27 18:04 -0500   stefan
    |    Add epsilon
    |
    o  2   989b4d060121   2009-04-27 18:04 -0500   durin42
    |    Add beta and delta.
    |
    o  1   081603921c3f   2009-04-27 18:04 -0500   durin42
    |    Add gamma
    |
    o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
         Add alpha
 
 If you run ``hg histedit --outgoing`` on the clone then it is the same
 as running ``hg histedit 836302820282``. If you need plan to push to a
 repository that Mercurial does not detect to be related to the source
 repo, you can add a ``--force`` option.
 """
 
 try:
     import cPickle as pickle
 except ImportError:
     import pickle
 import os
 
 from mercurial import bookmarks
 from mercurial import cmdutil
 from mercurial import discovery
 from mercurial import error
 from mercurial import copies
 from mercurial import context
 from mercurial import hg
 from mercurial import lock as lockmod
 from mercurial import node
 from mercurial import repair
 from mercurial import scmutil
 from mercurial import util
 from mercurial import merge as mergemod
 from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 
 testedwith = 'internal'
 
 # i18n: command names and abbreviations must remain untranslated
 editcomment = _("""# Edit history between %s and %s
 #
 # Commands:
 #  p, pick = use commit
 #  e, edit = use commit, but stop for amending
 #  f, fold = use commit, but fold into previous commit (combines N and N-1)
 #  d, drop = remove commit from history
 #  m, mess = edit message without changing commit content
 #
 """)
 
 def applychanges(ui, repo, ctx, opts):
     """Merge changeset from ctx (only) in the current working directory"""
     wcpar = repo.dirstate.parents()[0]
     if ctx.p1().node() == wcpar:
         # edition ar "in place" we do not need to make any merge,
         # just applies changes on parent for edition
         cmdutil.revert(ui, repo, ctx, (wcpar, node.nullid), all=True)
         stats = None
     else:
         try:
             # ui.forcemerge is an internal variable, do not document
             repo.ui.setconfig('ui', 'forcemerge', opts.get('tool', ''))
             stats = mergemod.update(repo, ctx.node(), True, True, False,
                                     ctx.p1().node())
         finally:
             repo.ui.setconfig('ui', 'forcemerge', '')
         repo.setparents(wcpar, node.nullid)
         repo.dirstate.write()
         # fix up dirstate for copies and renames
     cmdutil.duplicatecopies(repo, ctx.rev(), ctx.p1().rev())
     return stats
 
 def collapse(repo, first, last, commitopts):
     """collapse the set of revisions from first to last as new one.
 
     Expected commit options are:
         - message
         - date
         - username
     Edition of commit message is trigered in all case.
 
     This function works in memory."""
     ctxs = list(repo.set('%d::%d', first, last))
     if not ctxs:
         return None
     base = first.parents()[0]
 
     # commit a new version of the old changeset, including the update
     # collect all files which might be affected
     files = set()
     for ctx in ctxs:
         files.update(ctx.files())
 
     # Recompute copies (avoid recording a -> b -> a)
     copied = copies.pathcopies(first, last)
 
     # prune files which were reverted by the updates
     def samefile(f):
         if f in last.manifest():
             a = last.filectx(f)
             if f in base.manifest():
                 b = base.filectx(f)
                 return (a.data() == b.data()
                         and a.flags() == b.flags())
             else:
                 return False
         else:
             return f not in base.manifest()
     files = [f for f in files if not samefile(f)]
     # commit version of these files as defined by head
     headmf = last.manifest()
     def filectxfn(repo, ctx, path):
         if path in headmf:
             fctx = last[path]
             flags = fctx.flags()
             mctx = context.memfilectx(fctx.path(), fctx.data(),
                                       islink='l' in flags,
                                       isexec='x' in flags,
                                       copied=copied.get(path))
             return mctx
         raise IOError()
 
     if commitopts.get('message'):
         message = commitopts['message']
     else:
         message = first.description()
     user = commitopts.get('user')
     date = commitopts.get('date')
     extra = first.extra()
 
     parents = (first.p1().node(), first.p2().node())
     new = context.memctx(repo,
                          parents=parents,
                          text=message,
                          files=files,
                          filectxfn=filectxfn,
                          user=user,
                          date=date,
                          extra=extra)
     new._text = cmdutil.commitforceeditor(repo, new, [])
     return repo.commitctx(new)
 
 def pick(ui, repo, ctx, ha, opts):
     oldctx = repo[ha]
     if oldctx.parents()[0] == ctx:
         ui.debug('node %s unchanged\n' % ha)
         return oldctx, [], [], []
     hg.update(repo, ctx.node())
     stats = applychanges(ui, repo, oldctx, opts)
     if stats and stats[3] > 0:
         raise util.Abort(_('Fix up the change and run '
                            'hg histedit --continue'))
     # drop the second merge parent
     n = repo.commit(text=oldctx.description(), user=oldctx.user(),
                     date=oldctx.date(), extra=oldctx.extra())
     if n is None:
         ui.warn(_('%s: empty changeset\n')
                      % node.hex(ha))
         return ctx, [], [], []
     return repo[n], [n], [oldctx.node()], []
 
 
 def edit(ui, repo, ctx, ha, opts):
     oldctx = repo[ha]
     hg.update(repo, ctx.node())
     applychanges(ui, repo, oldctx, opts)
     raise util.Abort(_('Make changes as needed, you may commit or record as '
                        'needed now.\nWhen you are finished, run hg'
                        ' histedit --continue to resume.'))
 
 def fold(ui, repo, ctx, ha, opts):
     oldctx = repo[ha]
     hg.update(repo, ctx.node())
     stats = applychanges(ui, repo, oldctx, opts)
     if stats and stats[3] > 0:
         raise util.Abort(_('Fix up the change and run '
                            'hg histedit --continue'))
     n = repo.commit(text='fold-temp-revision %s' % ha, user=oldctx.user(),
                     date=oldctx.date(), extra=oldctx.extra())
     if n is None:
         ui.warn(_('%s: empty changeset')
                      % node.hex(ha))
         return ctx, [], [], []
     return finishfold(ui, repo, ctx, oldctx, n, opts, [])
 
 def finishfold(ui, repo, ctx, oldctx, newnode, opts, internalchanges):
     parent = ctx.parents()[0].node()
     hg.update(repo, parent)
     ### prepare new commit data
     commitopts = opts.copy()
     # username
     if ctx.user() == oldctx.user():
         username = ctx.user()
     else:
         username = ui.username()
     commitopts['user'] = username
     # commit message
     newmessage = '\n***\n'.join(
         [ctx.description()] +
         [repo[r].description() for r in internalchanges] +
         [oldctx.description()]) + '\n'
     commitopts['message'] = newmessage
     # date
     commitopts['date'] = max(ctx.date(), oldctx.date())
     n = collapse(repo, ctx, repo[newnode], commitopts)
     if n is None:
         return ctx, [], [], []
     hg.update(repo, n)
     return repo[n], [n], [oldctx.node(), ctx.node()], [newnode]
 
 def drop(ui, repo, ctx, ha, opts):
     return ctx, [], [repo[ha].node()], []
 
 
 def message(ui, repo, ctx, ha, opts):
     oldctx = repo[ha]
     hg.update(repo, ctx.node())
     stats = applychanges(ui, repo, oldctx, opts)
     if stats and stats[3] > 0:
         raise util.Abort(_('Fix up the change and run '
                            'hg histedit --continue'))
     message = oldctx.description() + '\n'
     message = ui.edit(message, ui.username())
     new = repo.commit(text=message, user=oldctx.user(), date=oldctx.date(),
                       extra=oldctx.extra())
     newctx = repo[new]
     if oldctx.node() != newctx.node():
         return newctx, [new], [oldctx.node()], []
     # We didn't make an edit, so just indicate no replaced nodes
     return newctx, [new], [], []
 
 actiontable = {'p': pick,
                'pick': pick,
                'e': edit,
                'edit': edit,
                'f': fold,
                'fold': fold,
                'd': drop,
                'drop': drop,
                'm': message,
                'mess': message,
                }
 
 @command('histedit',
     [('', 'commands', '',
       _('Read history edits from the specified file.')),
      ('c', 'continue', False, _('continue an edit already in progress')),
      ('k', 'keep', False,
       _("don't strip old nodes after edit is complete")),
      ('', 'abort', False, _('abort an edit in progress')),
      ('o', 'outgoing', False, _('changesets not found in destination')),
      ('f', 'force', False,
       _('force outgoing even for unrelated repositories')),
      ('r', 'rev', [], _('first revision to be edited'))],
      _("[PARENT]"))
 def histedit(ui, repo, *parent, **opts):
     """interactively edit changeset history
     """
     # TODO only abort if we try and histedit mq patches, not just
     # blanket if mq patches are applied somewhere
     mq = getattr(repo, 'mq', None)
     if mq and mq.applied:
         raise util.Abort(_('source has mq patches applied'))
 
     parent = list(parent) + opts.get('rev', [])
     if opts.get('outgoing'):
         if len(parent) > 1:
             raise util.Abort(
                 _('only one repo argument allowed with --outgoing'))
         elif parent:
             parent = parent[0]
 
         dest = ui.expandpath(parent or 'default-push', parent or 'default')
         dest, revs = hg.parseurl(dest, None)[:2]
         ui.status(_('comparing with %s\n') % util.hidepassword(dest))
 
         revs, checkout = hg.addbranchrevs(repo, repo, revs, None)
         other = hg.peer(repo, opts, dest)
 
         if revs:
             revs = [repo.lookup(rev) for rev in revs]
 
         parent = discovery.findcommonoutgoing(
             repo, other, [], force=opts.get('force')).missing[0:1]
     else:
         if opts.get('force'):
             raise util.Abort(_('--force only allowed with --outgoing'))
 
     if opts.get('continue', False):
         if len(parent) != 0:
             raise util.Abort(_('no arguments allowed with --continue'))
         (parentctxnode, created, replaced, tmpnodes,
          existing, rules, keep, topmost, replacemap) = readstate(repo)
         parentctx = repo[parentctxnode]
         existing = set(existing)
         parentctx = bootstrapcontinue(ui, repo, parentctx, existing,
                                       replacemap, rules, tmpnodes, created,
                                       replaced, opts)
     elif opts.get('abort', False):
         if len(parent) != 0:
             raise util.Abort(_('no arguments allowed with --abort'))
         (parentctxnode, created, replaced, tmpnodes,
          existing, rules, keep, topmost, replacemap) = readstate(repo)
         ui.debug('restore wc to old parent %s\n' % node.short(topmost))
         hg.clean(repo, topmost)
         cleanupnode(ui, repo, 'created', created)
         cleanupnode(ui, repo, 'temp', tmpnodes)
         os.unlink(os.path.join(repo.path, 'histedit-state'))
         return
     else:
         cmdutil.bailifchanged(repo)
         if os.path.exists(os.path.join(repo.path, 'histedit-state')):
             raise util.Abort(_('history edit already in progress, try '
                                '--continue or --abort'))
 
         topmost, empty = repo.dirstate.parents()
 
 
         if len(parent) != 1:
             raise util.Abort(_('histedit requires exactly one parent revision'))
         parent = scmutil.revsingle(repo, parent[0]).node()
 
         keep = opts.get('keep', False)
         revs = between(repo, parent, topmost, keep)
 
         ctxs = [repo[r] for r in revs]
         existing = [r.node() for r in ctxs]
         rules = opts.get('commands', '')
         if not rules:
             rules = '\n'.join([makedesc(c) for c in ctxs])
             rules += '\n\n'
             rules += editcomment % (node.short(parent), node.short(topmost))
             rules = ui.edit(rules, ui.username())
             # Save edit rules in .hg/histedit-last-edit.txt in case
             # the user needs to ask for help after something
             # surprising happens.
             f = open(repo.join('histedit-last-edit.txt'), 'w')
             f.write(rules)
             f.close()
         else:
             f = open(rules)
             rules = f.read()
             f.close()
         rules = [l for l in (r.strip() for r in rules.splitlines())
                  if l and not l[0] == '#']
         rules = verifyrules(rules, repo, ctxs)
 
         parentctx = repo[parent].parents()[0]
         keep = opts.get('keep', False)
         replaced = []
         replacemap = {}
         tmpnodes = []
         created = []
 
 
     while rules:
         writestate(repo, parentctx.node(), created, replaced,
                    tmpnodes, existing, rules, keep, topmost, replacemap)
         action, ha = rules.pop(0)
         ui.debug('histedit: processing %s %s\n' % (action, ha))
         (parentctx, created_, replaced_, tmpnodes_) = actiontable[action](
             ui, repo, parentctx, ha, opts)
 
         if replaced_:
             clen, rlen = len(created_), len(replaced_)
             if clen == rlen == 1:
                 ui.debug('histedit: exact replacement of %s with %s\n' % (
                     node.short(replaced_[0]), node.short(created_[0])))
 
                 replacemap[replaced_[0]] = created_[0]
             elif clen > rlen:
                 assert rlen == 1, ('unexpected replacement of '
                                    '%d changes with %d changes' % (rlen, clen))
                 # made more changesets than we're replacing
                 # TODO synthesize patch names for created patches
                 replacemap[replaced_[0]] = created_[-1]
                 ui.debug('histedit: created many, assuming %s replaced by %s' %
                          (node.short(replaced_[0]), node.short(created_[-1])))
             elif rlen > clen:
                 if not created_:
                     # This must be a drop. Try and put our metadata on
                     # the parent change.
                     assert rlen == 1
                     r = replaced_[0]
                     ui.debug('histedit: %s seems replaced with nothing, '
                             'finding a parent\n' % (node.short(r)))
                     pctx = repo[r].parents()[0]
                     if pctx.node() in replacemap:
                         ui.debug('histedit: parent is already replaced\n')
                         replacemap[r] = replacemap[pctx.node()]
                     else:
                         replacemap[r] = pctx.node()
                     ui.debug('histedit: %s best replaced by %s\n' % (
                         node.short(r), node.short(replacemap[r])))
                 else:
                     assert len(created_) == 1
                     for r in replaced_:
                         ui.debug('histedit: %s replaced by %s\n' % (
                             node.short(r), node.short(created_[0])))
                         replacemap[r] = created_[0]
             else:
                 assert False, (
                     'Unhandled case in replacement mapping! '
                     'replacing %d changes with %d changes' % (rlen, clen))
         created.extend(created_)
         replaced.extend(replaced_)
         tmpnodes.extend(tmpnodes_)
 
     hg.update(repo, parentctx.node())
 
     if not keep:
         if replacemap:
             movebookmarks(ui, repo, replacemap, tmpnodes, created)
             # TODO update mq state
         cleanupnode(ui, repo, 'replaced', replaced)
 
     cleanupnode(ui, repo, 'temp', tmpnodes)
     os.unlink(os.path.join(repo.path, 'histedit-state'))
     if os.path.exists(repo.sjoin('undo')):
         os.unlink(repo.sjoin('undo'))
 
 
 def bootstrapcontinue(ui, repo, parentctx, existing, replacemap, rules,
                       tmpnodes, created, replaced, opts):
-    currentparent, wantnull = repo.dirstate.parents()
-    # existing is the list of revisions initially considered by
-    # histedit. Here we use it to list new changesets, descendants
-    # of parentctx without an 'existing' changeset in-between. We
-    # also have to exclude 'existing' changesets which were
-    # previously dropped.
-    descendants = set(c.node() for c in
-            repo.set('(%d::) - %d', parentctx, parentctx))
-    notdropped = set(n for n in existing if n in descendants and
-            (n not in replacemap or replacemap[n] in descendants))
-    # Discover any nodes the user has added in the interim. We can
-    # miss changesets which were dropped and recreated the same.
-    newchildren = list(c.node() for c in repo.set(
-        'sort(%ln - (%ln or %ln::))', descendants, existing, notdropped))
     action, currentnode = rules.pop(0)
+    # is there any new commit between the expected parent and "."
+    #
+    # note: does not take non linear new change in account (but previous
+    #       implementation didn't used them anyway (issue3655)
+    newchildren = [c.node() for c in repo.set('(%d::.)', parentctx)]
+    if not newchildren:
+        # `parentctxnode` should match but no result. This means that
+        # currentnode is not a descendant from parentctxnode.
+        msg = _('working directory parent is not a descendant of %s')
+        hint = _('update to %s or descendant and run "hg histedit '
+                 '--continue" again') % parentctx
+        raise util.Abort(msg % parentctx, hint=hint)
+    newchildren.pop(0)  # remove parentctxnode
     if action in ('f', 'fold'):
         tmpnodes.extend(newchildren)
     else:
         created.extend(newchildren)
 
     m, a, r, d = repo.status()[:4]
     oldctx = repo[currentnode]
     message = oldctx.description() + '\n'
     if action in ('e', 'edit', 'm', 'mess'):
         message = ui.edit(message, ui.username())
     elif action in ('f', 'fold'):
         message = 'fold-temp-revision %s' % currentnode
     new = None
     if m or a or r or d:
         new = repo.commit(text=message, user=oldctx.user(),
                           date=oldctx.date(), extra=oldctx.extra())
 
     # If we're resuming a fold and we have new changes, mark the
     # replacements and finish the fold. If not, it's more like a
     # drop of the changesets that disappeared, and we can skip
     # this step.
     if action in ('f', 'fold') and (new or newchildren):
         if new:
             tmpnodes.append(new)
         else:
             new = newchildren[-1]
         (parentctx, created_, replaced_, tmpnodes_) = finishfold(
             ui, repo, parentctx, oldctx, new, opts, newchildren)
         replaced.extend(replaced_)
         created.extend(created_)
         tmpnodes.extend(tmpnodes_)
     elif action not in ('d', 'drop'):
         if new != oldctx.node():
             replaced.append(oldctx.node())
         if new:
             if new != oldctx.node():
                 created.append(new)
             parentctx = repo[new]
     return parentctx
 
 
 def between(repo, old, new, keep):
     """select and validate the set of revision to edit
 
     When keep is false, the specified set can't have children."""
     revs = [old]
     current = old
     while current != new:
         ctx = repo[current]
         if not keep and len(ctx.children()) > 1:
             raise util.Abort(_('cannot edit history that would orphan nodes'))
         if len(ctx.parents()) != 1 and ctx.parents()[1] != node.nullid:
             raise util.Abort(_("can't edit history with merges"))
         if not ctx.children():
             current = new
         else:
             current = ctx.children()[0].node()
             revs.append(current)
     if len(repo[current].children()) and not keep:
         raise util.Abort(_('cannot edit history that would orphan nodes'))
     return revs
 
 
 def writestate(repo, parentctxnode, created, replaced,
                tmpnodes, existing, rules, keep, topmost, replacemap):
     fp = open(os.path.join(repo.path, 'histedit-state'), 'w')
     pickle.dump((parentctxnode, created, replaced,
                  tmpnodes, existing, rules, keep, topmost, replacemap),
                 fp)
     fp.close()
 
 def readstate(repo):
     """Returns a tuple of (parentnode, created, replaced, tmp, existing, rules,
                            keep, topmost, replacemap ).
     """
     fp = open(os.path.join(repo.path, 'histedit-state'))
     return pickle.load(fp)
 
 
 def makedesc(c):
     """build a initial action line for a ctx `c`
 
     line are in the form:
 
       pick <hash> <rev> <summary>
     """
     summary = ''
     if c.description():
         summary = c.description().splitlines()[0]
     line = 'pick %s %d %s' % (c, c.rev(), summary)
     return line[:80]  # trim to 80 chars so it's not stupidly wide in my editor
 
 def verifyrules(rules, repo, ctxs):
     """Verify that there exists exactly one edit rule per given changeset.
 
     Will abort if there are to many or too few rules, a malformed rule,
     or a rule on a changeset outside of the user-given range.
     """
     parsed = []
     if len(rules) != len(ctxs):
         raise util.Abort(_('must specify a rule for each changeset once'))
     for r in rules:
         if ' ' not in r:
             raise util.Abort(_('malformed line "%s"') % r)
         action, rest = r.split(' ', 1)
         if ' ' in rest.strip():
             ha, rest = rest.split(' ', 1)
         else:
             ha = r.strip()
         try:
             if repo[ha] not in ctxs:
                 raise util.Abort(
                     _('may not use changesets other than the ones listed'))
         except error.RepoError:
             raise util.Abort(_('unknown changeset %s listed') % ha)
         if action not in actiontable:
             raise util.Abort(_('unknown action "%s"') % action)
         parsed.append([action, ha])
     return parsed
 
 def movebookmarks(ui, repo, replacemap, tmpnodes, created):
     """Move bookmark from old to newly created node"""
     ui.note(_('histedit: Should update metadata for the following '
               'changes:\n'))
 
     def copybms(old, new):
         if old in tmpnodes or old in created:
             # can't have any metadata we'd want to update
             return
         while new in replacemap:
             new = replacemap[new]
         ui.note(_('histedit:  %s to %s\n') % (node.short(old),
                                               node.short(new)))
         octx = repo[old]
         marks = octx.bookmarks()
         if marks:
             ui.note(_('histedit:     moving bookmarks %s\n') %
                       ', '.join(marks))
             for mark in marks:
                 repo._bookmarks[mark] = new
             bookmarks.write(repo)
 
     # We assume that bookmarks on the tip should remain
     # tipmost, but bookmarks on non-tip changesets should go
     # to their most reasonable successor. As a result, find
     # the old tip and new tip and copy those bookmarks first,
     # then do the rest of the bookmark copies.
     oldtip = sorted(replacemap.keys(), key=repo.changelog.rev)[-1]
     newtip = sorted(replacemap.values(), key=repo.changelog.rev)[-1]
     copybms(oldtip, newtip)
 
     for old, new in sorted(replacemap.iteritems()):
         copybms(old, new)
 
 def cleanupnode(ui, repo, name, nodes):
     """strip a group of nodes from the repository
 
     The set of node to strip may contains unknown nodes."""
     ui.debug('should strip %s nodes %s\n' %
              (name, ', '.join([node.short(n) for n in nodes])))
     lock = None
     try:
         lock = repo.lock()
         # Find all node that need to be stripped
         # (we hg %lr instead of %ln to silently ignore unknown item
         nm = repo.changelog.nodemap
         nodes = [n for n in nodes if n in nm]
         roots = [c.node() for c in repo.set("roots(%ln)", nodes)]
         for c in roots:
             # We should process node in reverse order to strip tip most first.
             # but this trigger a bug in changegroup hook.
             # This would reduce bundle overhead
             repair.strip(ui, repo, c)
     finally:
         lockmod.release(lock)
 

tests/test-histedit-edit.t

@@ -1,178 +1,191 b''
   $ . "$TESTDIR/histedit-helpers.sh"
 
   $ cat >> $HGRCPATH <<EOF
   > [extensions]
   > graphlog=
   > histedit=
   > EOF
 
   $ EDITED="$TESTTMP/editedhistory"
   $ cat > $EDITED <<EOF
   > pick 177f92b77385 c
   > pick 055a42cdd887 d
   > edit e860deea161a e
   > pick 652413bf663e f
   > EOF
   $ initrepo ()
   > {
   >     hg init r
   >     cd r
   >     for x in a b c d e f ; do
   >         echo $x > $x
   >         hg add $x
   >         hg ci -m $x
   >     done
   > }
 
   $ initrepo
 
 log before edit
   $ hg log --graph
   @  changeset:   5:652413bf663e
   |  tag:         tip
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     f
   |
   o  changeset:   4:e860deea161a
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     e
   |
   o  changeset:   3:055a42cdd887
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     d
   |
   o  changeset:   2:177f92b77385
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     c
   |
   o  changeset:   1:d2ae7f538514
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     b
   |
   o  changeset:   0:cb9a9f314b8b
      user:        test
      date:        Thu Jan 01 00:00:00 1970 +0000
      summary:     a
   
 
 edit the history
   $ HGEDITOR="cat \"$EDITED\" > " hg histedit 177f92b77385 2>&1 | fixbundle
   0 files updated, 0 files merged, 2 files removed, 0 files unresolved
   abort: Make changes as needed, you may commit or record as needed now.
   When you are finished, run hg histedit --continue to resume.
 
+Go at a random point and try to continue
+
+  $ hg id -n
+  3+
+  $ hg up 0
+  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
+  $ HGEDITOR='echo foobaz > ' hg histedit --continue
+  abort: working directory parent is not a descendant of 055a42cdd887
+  (update to 055a42cdd887 or descendant and run "hg histedit --continue" again)
+  [255]
+  $ hg up 3
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
 commit, then edit the revision
   $ hg ci -m 'wat'
   created new head
   $ echo a > e
   $ HGEDITOR='echo foobaz > ' hg histedit --continue 2>&1 | fixbundle
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg log --graph
   @  changeset:   6:bf757c081cd0
   |  tag:         tip
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     f
   |
   o  changeset:   5:d6b15fed32d4
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     foobaz
   |
   o  changeset:   4:1a60820cd1f6
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     wat
   |
   o  changeset:   3:055a42cdd887
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     d
   |
   o  changeset:   2:177f92b77385
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     c
   |
   o  changeset:   1:d2ae7f538514
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     b
   |
   o  changeset:   0:cb9a9f314b8b
      user:        test
      date:        Thu Jan 01 00:00:00 1970 +0000
      summary:     a
   
 
   $ hg cat e
   a
 
   $ cat > $EDITED <<EOF
   > edit bf757c081cd0 f
   > EOF
   $ HGEDITOR="cat \"$EDITED\" > " hg histedit tip 2>&1 | fixbundle
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   abort: Make changes as needed, you may commit or record as needed now.
   When you are finished, run hg histedit --continue to resume.
   $ hg status
   A f
   $ HGEDITOR='true' hg histedit --continue
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg status
 
 log after edit
   $ hg log --limit 1
   changeset:   6:bf757c081cd0
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     f
   
 
 say we'll change the message, but don't.
   $ cat > ../edit.sh <<EOF
   > cat "\$1" | sed s/pick/mess/ > tmp
   > mv tmp "\$1"
   > EOF
   $ HGEDITOR="sh ../edit.sh" hg histedit tip 2>&1 | fixbundle
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg status
   $ hg log --limit 1
   changeset:   6:bf757c081cd0
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     f
   
 
 modify the message
   $ cat > $EDITED <<EOF
   > mess bf757c081cd0 f
   > EOF
   $ HGEDITOR="cat \"$EDITED\" > " hg histedit tip 2>&1 | fixbundle
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg status
   $ hg log --limit 1
   changeset:   6:0b16746f8e89
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     mess bf757c081cd0 f
   
 
 rollback should not work after a histedit
   $ hg rollback
   no rollback information available
   [1]
 
   $ cd ..