merge --uncommitted on a branch that is an ancestor of the one you are merging into breaks

[Vincent Ladeuil]

#!/bin/bash
rm -fr bug
mkdir bug
cd bug
bzr init base
cd base
echo blabla > a
bzr add a
bzr commit -m 'Adding a'
cd ..
bzr branch base branch
cd base
# bzr mv a b
echo talk properly > a
cd ../branch
bzr merge --uncommitted ../base

Results in:

bzr: ERROR: exceptions.TypeError: sequence item 2: expected string, NoneType found

Traceback (most recent call last):
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 729, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 691, in run_bzr
    ret = run(*run_argv)
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 389, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/v/home/vila/src/bzr.dev/bzrlib/builtins.py", line 2738, in run
    change_reporter=change_reporter)
  File "/v/home/vila/src/bzr.dev/bzrlib/builtins.py", line 3804, in _merge_helper
    merger.set_pending()
  File "/v/home/vila/src/bzr.dev/bzrlib/merge.py", line 168, in set_pending
    self._add_parent()
  File "/v/home/vila/src/bzr.dev/bzrlib/merge.py", line 183, in _add_parent
    allow_leftmost_as_ghost=True)
  File "/v/home/vila/src/bzr.dev/bzrlib/mutabletree.py", line 52, in tree_write_locked
    self.unlock()
  File "/v/home/vila/src/bzr.dev/bzrlib/workingtree_4.py", line 1121, in unlock
    self.flush()
  File "/v/home/vila/src/bzr.dev/bzrlib/workingtree_4.py", line 312, in flush
    self.current_dirstate().save()
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1728, in save
    self._state_file.writelines(self.get_lines())
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1221, in get_lines
    lines.append(self._get_parents_line(self.get_parent_ids()))
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1233, in _get_parents_line
    return '\0'.join([str(len(parent_ids))] + parent_ids)
TypeError: sequence item 2: expected string, NoneType found

[Vincent Ladeuil (vila)]

If I'm wrong about dirstate being the culprit, feel free to change the description.

[Aaron Bentley (abentley)]

This report doesn't make clear what the problems are.

[Vincent Ladeuil (vila)]

Yes, sorry about that.

The problem is that running the given script issues a trace back:

added a
added a
Committed revision 1.
Branched 1 revision(s).
 M a
All changes applied successfully.
bzr: ERROR: exceptions.TypeError: sequence item 2: expected string, NoneType found

Traceback (most recent call last):
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 729, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 691, in run_bzr
    ret = run(*run_argv)
  File "/v/home/vila/src/bzr.dev/bzrlib/commands.py", line 389, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/v/home/vila/src/bzr.dev/bzrlib/builtins.py", line 2738, in run
    change_reporter=change_reporter)
  File "/v/home/vila/src/bzr.dev/bzrlib/builtins.py", line 3804, in _merge_helper
    merger.set_pending()
  File "/v/home/vila/src/bzr.dev/bzrlib/merge.py", line 168, in set_pending
    self._add_parent()
  File "/v/home/vila/src/bzr.dev/bzrlib/merge.py", line 183, in _add_parent
    allow_leftmost_as_ghost=True)
  File "/v/home/vila/src/bzr.dev/bzrlib/mutabletree.py", line 52, in tree_write_locked
    self.unlock()
  File "/v/home/vila/src/bzr.dev/bzrlib/workingtree_4.py", line 1121, in unlock
    self.flush()
  File "/v/home/vila/src/bzr.dev/bzrlib/workingtree_4.py", line 312, in flush
    self.current_dirstate().save()
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1728, in save
    self._state_file.writelines(self.get_lines())
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1221, in get_lines
    lines.append(self._get_parents_line(self.get_parent_ids()))
  File "/v/home/vila/src/bzr.dev/bzrlib/dirstate.py", line 1233, in _get_parents_line
    return '\0'.join([str(len(parent_ids))] + parent_ids)
TypeError: sequence item 2: expected string, NoneType found

bzr 0.19.0dev0 on python 2.4.4.candidate.1 (linux2)
arguments: ['/home/vila/bin/bzr', 'merge', '--uncommitted', '../base']

** please send this report to <email address hidden>
/v/home/vila/src/bzr.dev/bzrlib/lockable_files.py:110: UserWarning: file group LockableFiles(<bzrlib.transport.local.LocalTransport url=file:///home/vila/tmp/bug/branch/.bzr/checkout/>) was not explicitly unlocked
  warn("file group %r was not explicitly unlocked" % self)
/v/home/vila/src/bzr.dev/bzrlib/lock.py:79: UserWarning: lock on <open file u'/home/vila/tmp/bug/branch/.bzr/checkout/dirstate', mode 'rb+' at 0xb777f7b8> not released
  warn("lock on %r not released" % self.f)

[Wouter van Heyst (larstiq)]

This is similar, but not quite, to something I mailed about on the 14th. Picking this one up
and writing tests for both.

[Wouter van Heyst (larstiq)]

bzr-bisect is a little broken, but it still helped to determine this got broken in r2617, 'Improve merge speed'. Sepcifically <email address hidden>
removed the checking for self.other_rev_id being None.

[Vincent Ladeuil (vila)]

Fixed in bzr.dev @ 2645