Haystack + Whoosh IndexError: Index was created on an architecture with different data sizes

When rebuilding my indices via ./manage.py rebuild_index I get this error:

Traceback (most recent call last):
  File "manage.py", line 11, in <module>
    execute_manager(settings)
  File "/Library/Python/2.6/site-packages/django/core/management/__init__.py", line 438, in execute_manager
    utility.execute()
  File "/Library/Python/2.6/site-packages/django/core/management/__init__.py", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Library/Python/2.6/site-packages/django/core/management/base.py", line 191, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Library/Python/2.6/site-packages/django/core/manageme开发者_JS百科nt/base.py", line 218, in execute
    output = self.handle(*args, **options)
  File "/Library/Python/2.6/site-packages/haystack/management/commands/rebuild_index.py", line 13, in handle
    call_command('clear_index', **options)
  File "/Library/Python/2.6/site-packages/django/core/management/__init__.py", line 166, in call_command
    return klass.execute(*args, **defaults)
  File "/Library/Python/2.6/site-packages/django/core/management/base.py", line 218, in execute
    output = self.handle(*args, **options)
  File "/Library/Python/2.6/site-packages/haystack/management/commands/clear_index.py", line 38, in handle
    sb.clear()
  File "/Library/Python/2.6/site-packages/haystack/backends/whoosh_backend.py", line 197, in clear
    self.setup()
  File "/Library/Python/2.6/site-packages/haystack/backends/whoosh_backend.py", line 105, in setup
    self.index = self.storage.open_index(schema=self.schema)
  File "/Library/Python/2.6/site-packages/Whoosh-0.3.18-py2.6.egg/whoosh/filedb/filestore.py", line 48, in open_index
  File "/Library/Python/2.6/site-packages/Whoosh-0.3.18-py2.6.egg/whoosh/filedb/fileindex.py", line 94, in __init__
  File "/Library/Python/2.6/site-packages/Whoosh-0.3.18-py2.6.egg/whoosh/filedb/fileindex.py", line 173, in _read
IndexError: Index was created on an architecture with different data sizes

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You have probably downgraded from whoosh 1.0.0 to 0.3.18, but there are some buggy index files already created at the path you defined by HAYSTACK_WHOOSH_PATH. Just make that directory empty and try again.