Branch fails from 'pack-0.92' repo to 'rich-root-pack' repo

[Ben Finney]

Aaron Bentley <aaron at aaronbentley.com> writes:

> Ben Finney wrote:
> > Then what is the "it" which "went into 1.5", and how does it relate to
> > the above work?
> 
> "It" was ensuring that all branches, even weird ones like BE can be
> converted into rich-root formats.

Based on the above, then, I understand that Bazaar 1.5 should be able
to convert arbitrary older branches to rich-root formats.

Should that hold for, say, using 'bzr upgrade' to convert a shared
repository in 'dirstate-with-subtree' format to one of
'rich-root-pack' or 'rich-root' format?

But, no such luck:

=====
$ bzr version
Bazaar (bzr) 1.5
[…]

$ bzr info .
Shared repository with trees (format: dirstate-with-subtree)
Location:
  shared repository: .

$ bzr upgrade --rich-root-pack .
starting upgrade of file:///home/benf/Projects.BROKEN-REPO/
making backup of tree history
file:///home/benf/Projects.BROKEN-REPO/.bzr has been backed up to file:///home/benf/Projects.BROKEN-REPO/backup.bzr
if conversion fails, you can move this directory back to .bzr
if it succeeds, you can remove this directory if you wish
starting repository conversion
bzr: ERROR: Cannot convert to format <RepositoryFormatKnitPack4>.  Does not support nested trees

$ rm -r .bzr/
$ mv backup.bzr/ .bzr/

$ bzr upgrade --rich-root .
starting upgrade of file:///home/benf/Projects.BROKEN-REPO/
making backup of tree history
file:///home/benf/Projects.BROKEN-REPO/.bzr has been backed up to file:///home/benf/Projects.BROKEN-REPO/backup.bzr
if conversion fails, you can move this directory back to .bzr
if it succeeds, you can remove this directory if you wish
starting repository conversion                                                                                                             
bzr: ERROR: Cannot convert to format <RepositoryFormatKnit4>.  Does not support nested trees                                               

$ rm -r .bzr/
$ mv backup.bzr/ .bzr/

=====

What am I missing?

-- 
 \      “If society were bound to invent technologies which could only |
  `\   be used entirely within the law, then we would still be sitting |
_o__)       in caves sucking our feet.” —Gene Kan, creator of Gnutella |
Ben Finney