bzr log failure when filename specified and ghosts present.

I guess it is a regression since this works perfectly with bzr 1.3

bzr: ERROR: exceptions.KeyError: '<email address hidden>'

Traceback (most recent call last):
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/commands.py", line 834, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/commands.py", line 790, in run_bzr
    ret = run(*run_argv)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/commands.py", line 492, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/commands.py", line 800, in ignore_pipe
    result = func(*args, **kwargs)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/builtins.py", line 1789, in run
    limit=limit)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/log.py", line 185, in show_log
    start_revision, end_revision, search, limit)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/log.py", line 215, in _show_log
    allow_single_merge_revision)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/log.py", line 282, in calculate_view_revisions
    view_revisions)
  File "/home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/log.py", line 482, in _filter_revisions_touching_file_id
    rev_ancestry = rev_ancestry.union(ancestry[parent])
KeyError: '<email address hidden>'

bzr 1.4dev on python 2.5.1 (linux2)
arguments: ['/home/xma/usr/src/BZRed/bzr/bzr.dev/bzr', 'log', '--limit=30', '--short', 'bzrlib/mail_client.py']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'en_US.UTF-8'
plugins:
  bzrtools /home/xma/.bazaar/plugins/bzrtools [1.3.0]
  fastimport /home/xma/.bazaar/plugins/fastimport [unknown]
  launchpad /home/xma/usr/src/BZRed/bzr/bzr.dev/bzrlib/plugins/launchpad [unknown]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred

This is a ghost handling issue. The code that determines whether a given file is affected by a revision may now encounter ghosts, but cannot handle them properly. The issue can be reproduced without using --limit or --short

The fix is actually pretty trivial:

The _filter_revisions_touching_file_id just didn't handle the case where a parent could be referenced, but not already computed in the ancestry.

I'll put together a test, and submit it:
=== modified file 'bzrlib/log.py'
--- bzrlib/log.py 2008-03-28 03:54:40 +0000
+++ bzrlib/log.py 2008-04-18 17:37:53 +0000
@@ -479,6 +479,8 @@
             if rev in weave_modifed_revisions:
                 rev_ancestry.add(rev)
             for parent in parents:
+ if parent not in ancestry: # Ghost
+ continue
                 rev_ancestry = rev_ancestry.union(ancestry[parent])
         ancestry[rev] = rev_ancestry