Comment 4 for bug 408824

The attached branch gives a better message and shows the failures are actually like this:

======================================================================
FAIL: test_upgrade_explicit_knit (bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches)

vvvv[log from bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit]
5.309 creating repository in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/.bzr/.
5.314 creating branch <bzrlib.branch.BzrBranchFormat5 object at 0xb2dad8c> in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/.bzr/
5.325 opening working tree '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch'
5.326 failed to open /tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/.bzr/checkout/stat-cache: [Errno 2] No such file or directory: u'/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/.bzr/checkout/stat-cache'
5.326 write hc
5.332 run bzr: ['upgrade', '--format=knit', 'file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/']
5.332 bzr arguments: ['upgrade', '--format=knit', 'file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit/work/metadir_weave_branch/']
5.336 encoding stdout as sys.stdout encoding 'UTF-8'
5.344 Traceback (most recent call last):
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1131, in run_bzr_catch_user_errors
    return run_bzr(argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1030, in run_bzr
    ret = run(*run_argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 647, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/builtins.py", line 3140, in run
    upgrade(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 85, in upgrade
    Convert(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 40, in __init__
    self.convert()
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 74, in convert
    self.bzrdir.check_conversion_target(format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/bzrdir.py", line 134, in check_conversion_target
    source_repo_format.check_conversion_target(target_repo_format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/repofmt/groupcompress_repo.py", line 1108, in check_conversion_target
    from_format=self)
BadConversionTarget: Cannot convert from format <RepositoryFormat2a> to format <RepositoryFormatKnit1>. Does not support rich root data.

5.344 errors:
'bzr: ERROR: Cannot convert from format <RepositoryFormat2a> to format <RepositoryFormatKnit1>. Does not support rich root data.\n'
5.351 opening working tree '/tmp/testbzr-boa9Al.tmp'

^^^^[log from bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_explicit_knit]
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/tests/blackbox/test_upgrade.py", line 138, in test_upgrade_explicit_knit
    ['upgrade', '--format=knit', url])
AssertionError: Unexpected return code
not equal:
a = 0
b = 3

======================================================================
FAIL: test_upgrade_repo (bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches)

vvvv[log from bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_repo]
5.411 run bzr: ['init-repository', '--format=metaweave', 'repo']
5.412 bzr arguments: ['init-repository', '--format=metaweave', 'repo']
5.415 encoding stdout as sys.stdout encoding 'UTF-8'
5.418 creating repository in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_repo/work/repo/.bzr/.
5.428 output:
'Shared repository with trees (format: metaweave)\nLocation:\n shared repository: repo\n'
5.428 run bzr: ['upgrade', '--format=knit', 'repo']
5.428 bzr arguments: ['upgrade', '--format=knit', 'repo']
5.432 encoding stdout as sys.stdout encoding 'UTF-8'
5.435 Traceback (most recent call last):
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1131, in run_bzr_catch_user_errors
    return run_bzr(argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1030, in run_bzr
    ret = run(*run_argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 647, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/builtins.py", line 3140, in run
    upgrade(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 85, in upgrade
    Convert(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 40, in __init__
    self.convert()
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 74, in convert
    self.bzrdir.check_conversion_target(format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/bzrdir.py", line 134, in check_conversion_target
    source_repo_format.check_conversion_target(target_repo_format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/repofmt/groupcompress_repo.py", line 1108, in check_conversion_target
    from_format=self)
BadConversionTarget: Cannot convert from format <RepositoryFormat2a> to format <RepositoryFormatKnit1>. Does not support rich root data.

5.435 errors:
'bzr: ERROR: Cannot convert from format <RepositoryFormat2a> to format <RepositoryFormatKnit1>. Does not support rich root data.\n'
5.440 opening working tree '/tmp/testbzr-boa9Al.tmp'

^^^^[log from bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_repo]
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/tests/blackbox/test_upgrade.py", line 155, in test_upgrade_repo
    self.run_bzr('upgrade --format=knit repo')
AssertionError: Unexpected return code
not equal:
a = 0
b = 3

======================================================================
FAIL: test_upgrade_up_to_date (bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches)

vvvv[log from bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date]
5.456 creating repository in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch/.bzr/.
5.461 creating branch <bzrlib.branch.BzrBranchFormat7 object at 0xb34836c> in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch/.bzr/
5.476 trying to create missing lock '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch/.bzr/checkout/dirstate'
5.476 opening working tree '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch'
5.492 opening working tree '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch'
5.497 creating branch reference in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_checkout/.bzr/
5.505 trying to create missing lock '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_checkout/.bzr/checkout/dirstate'
5.505 opening working tree '/tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_checkout'
5.514 run bzr: ['upgrade', 'current_format_branch']
5.514 bzr arguments: ['upgrade', 'current_format_branch']
5.517 encoding stdout as sys.stdout encoding 'UTF-8'
5.541 creating repository in file:///tmp/testbzr-boa9Al.tmp/bzrlib.tests.blackbox.test_upgrade.TestWithUpgradableBranches.test_upgrade_up_to_date/work/current_format_branch/.bzr/.
5.551 Traceback (most recent call last):
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1131, in run_bzr_catch_user_errors
    return run_bzr(argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 1030, in run_bzr
    ret = run(*run_argv)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/commands.py", line 647, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/builtins.py", line 3140, in run
    upgrade(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 85, in upgrade
    Convert(url, format)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 40, in __init__
    self.convert()
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/upgrade.py", line 79, in convert
    self.bzrdir = converter.convert(self.bzrdir, self.pb)
  File "/home/mbp/bzr/408824-test-upgrade/bzrlib/bzrdir.py", line 3043, in convert
    branch._format)
BadConversionTarget: Cannot convert from format Branch format 7 to format <class 'bzrlib.branch.BzrBranchFormat6'>. No converter