Changing usernames

        Hi,

        I am in the process of moving over an existing
repository. However, I would like to change the usernames
that the committers used to match their new usernames.
        I thought using svn dump to dump repo to a file, changing
the username, and them uploading the file. However,
the dump tracks the length of the strings so I cannot change
it to longer/shorter usernames.
        How can I change the usernames?
        Thank You.

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Artur Kedzierski