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Per #908424: Drupal 7 port of Administer Users by Role there is no upgrade path for D6 -> D7 yet, so one needs to be added.
The D6 version is no longer supported. I don't use D6 and am not in a position to do this task. If someone else wants to volunteer, that would be fine, but that's not happened so far in several years! Closing the task, but please re-open if you are offering to do it.
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