bookmarks: Avoid unconditional forwarding of bookmarks for the null revision

This patch fixes the following minor problem:

% hg bookmark -r null test
% hg bookmarks
   test                      -1:000000000000
[...]
% hg commit
% hg bookmarks
 * test                      17:861ce7a241f9

That is: Bookmarks referring to the null revision are always forwarded
to the current revision.

hgext/bookmarks.py

@@ -1,227 +1,229 b''
 # Mercurial extension to provide the 'hg bookmark' command
 #
 # Copyright 2008 David Soria Parra <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 '''mercurial bookmarks
 
 Mercurial bookmarks are local moveable pointers to changesets. Every
 bookmark points to a changeset identified by its hash. If you commit a
 changeset that is based on a changeset that has a bookmark on it, the
 bookmark is forwarded to the new changeset.
 
 It is possible to use bookmark names in every revision lookup (e.g. hg
 merge, hg update).
 '''
 
 from mercurial.commands import templateopts, hex, short
 from mercurial.i18n import _
 from mercurial import cmdutil, util, commands, changelog
-from mercurial.node import nullrev
+from mercurial.node import nullid, nullrev
 from mercurial.repo import RepoError
 import mercurial, mercurial.localrepo, mercurial.repair, os
 
 def parse(repo):
     '''Parse .hg/bookmarks file and return a dictionary
 
     Bookmarks are stored as {HASH}\s{NAME}\n (localtags format) values
     in the .hg/bookmarks file. They are read by the parse() method and
     returned as a dictionary with name => hash values.
 
     The parsed dictionary is cached until a write() operation is done.
     '''
     try:
         if repo._bookmarks:
             return repo._bookmarks
         repo._bookmarks = {}
         for line in repo.opener('bookmarks'):
             sha, refspec = line.strip().split(' ', 1)
             repo._bookmarks[refspec] = repo.lookup(sha)
     except:
         pass
     return repo._bookmarks
 
 def write(repo, refs):
     '''Write bookmarks
 
     Write the given bookmark => hash dictionary to the .hg/bookmarks file
     in a format equal to those of localtags.
 
     We also store a backup of the previous state in undo.bookmarks that
     can be copied back on rollback.
     '''
     if os.path.exists(repo.join('bookmarks')):
         util.copyfile(repo.join('bookmarks'), repo.join('undo.bookmarks'))
     file = repo.opener('bookmarks', 'w+')
     for refspec, node in refs.items():
         file.write("%s %s\n" % (hex(node), refspec))
     file.close()
 
 def bookmark(ui, repo, mark=None, rev=None, force=False, delete=False, rename=None):
     '''mercurial bookmarks
 
     Bookmarks are pointers to certain commits that move when
     commiting. Bookmarks are local. They can be renamed, copied and
     deleted. It is possible to use bookmark names in 'hg merge' and 'hg
     update' to update to a given bookmark.
 
     You can use 'hg bookmark [NAME]' to set a bookmark on the current tip
     with the given name. If you specify a second [NAME] the bookmark is
     set to the bookmark that has that name. You can also pass revision
     identifiers to set bookmarks too.
     '''
     hexfn = ui.debugflag and hex or short
     marks = parse(repo)
     cur   = repo.changectx('.').node()
 
     if rename:
         if rename not in marks:
             raise util.Abort(_("a bookmark of this name does not exist"))
         if mark in marks and not force:
             raise util.Abort(_("a bookmark of the same name already exists"))
         if mark is None:
             raise util.Abort(_("new bookmark name required"))
         marks[mark] = marks[rename]
         del marks[rename]
         write(repo, marks)
         return
 
     if delete:
         if mark == None:
             raise util.Abort(_("bookmark name required"))
         if mark not in marks:
             raise util.Abort(_("a bookmark of this name does not exist"))
         del marks[mark]
         write(repo, marks)
         return
 
     if mark != None:
         if mark.strip().count("\n") > 0:
             raise Exception("bookmark cannot contain newlines")
         if mark in marks and not force:
             raise util.Abort(_("a bookmark of the same name already exists"))
         if ((mark in repo.branchtags() or mark == repo.dirstate.branch())
             and not force):
             raise util.Abort(
                 _("a bookmark cannot have the name of an existing branch"))
         if rev:
             marks[mark] = repo.lookup(rev)
         else:
             marks[mark] = repo.changectx('.').node()
         write(repo, marks)
         return
 
     if mark == None:
         if len(marks) == 0:
             ui.status("no bookmarks set\n")
         else:
             for bmark, n in marks.iteritems():
                 prefix = (n == cur) and '*' or ' '
                 ui.write(" %s %-25s %d:%s\n" % (
                     prefix, bmark, repo.changelog.rev(n), hexfn(n)))
         return
 
 def _revstostrip(changelog, node):
     srev = changelog.rev(node)
     tostrip = [srev]
     saveheads = []
     for r in xrange(srev, changelog.rev(changelog.tip()) + 1):
         parents = changelog.parentrevs(r)
         if parents[0] in tostrip or parents[1] in tostrip:
             tostrip.append(r)
             if parents[1] != nullrev:
                 for p in parents:
                     if p not in tostrip and p > striprev:
                         saveheads.append(p)
     return [r for r in tostrip if r not in saveheads]
 
 def strip(ui, repo, node, backup="all"):
     """Strip bookmarks if revisions are stripped using
     the mercurial.strip method. This usually happens during
     qpush and qpop"""
     revisions = _revstostrip(repo.changelog, node)
     marks = parse(repo)
     update = []
     for mark, n in marks.items():
         if repo.changelog.rev(n) in revisions:
             update.append(mark)
     result = oldstrip(ui, repo, node, backup)
     if len(update) > 0:
         for m in update:
             marks[m] = repo.changectx('.').node()
         write(repo, marks)
 
 oldstrip = mercurial.repair.strip
 mercurial.repair.strip = strip
 
 def reposetup(ui, repo):
     if not isinstance(repo, mercurial.localrepo.localrepository):
         return
 
     # init a bookmark cache as otherwise we would get a infinite reading
     # in lookup()
     repo._bookmarks = None
 
     class bookmark_repo(repo.__class__):
         def rollback(self):
             if os.path.exists(self.join('undo.bookmarks')):
                 util.rename(self.join('undo.bookmarks'), self.join('bookmarks'))
             return super(bookmark_repo, self).rollback()
 
         def lookup(self, key):
             if self._bookmarks is None:
                 self._bookmarks = parse(self)
             if key in self._bookmarks:
                 key = self._bookmarks[key]
             return super(bookmark_repo, self).lookup(key)
 
         def commit(self, *k, **kw):
             """Add a revision to the repository and
             move the bookmark"""
             node  = super(bookmark_repo, self).commit(*k, **kw)
             parents = repo.changelog.parents(node)
+            if parents[1] == nullid:
+                parents = (parents[0],)
             marks = parse(repo)
             update = False
             for mark, n in marks.items():
                 if n in parents:
                     marks[mark] = node
                     update = True
             if update:
                 write(repo, marks)
             return node
 
         def addchangegroup(self, source, srctype, url, emptyok=False):
             try:
                 onode = repo.changectx('.').node()
             except RepoError, inst:
                 pass
 
             result = super(bookmark_repo, self).addchangegroup(
                 source, srctype, url, emptyok)
             if result > 1:
                 # We have more heads than before
                 return result
             node = repo.changelog.tip()
             marks = parse(repo)
             update = False
             for mark, n in marks.items():
                 if n == onode:
                     marks[mark] = node
                     update = True
             if update:
                 write(repo, marks)
             return result
 
     repo.__class__ = bookmark_repo
 
 cmdtable = {
     "bookmarks":
         (bookmark,
          [('f', 'force', False, _('force')),
           ('r', 'rev', '', _('revision')),
           ('d', 'delete', False, _('delete a given bookmark')),
           ('m', 'rename', '', _('rename a given bookmark'))],
          _('hg bookmarks [-d] [-m NAME] [-r NAME] [NAME]')),
 }