Fixing issue where duplicate user causes error instead of new screen on setup.pl.

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extra : source : 014eba2ce9336fa45c4d5ceb9381547da57a915a
Updating changelog

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extra : source : f5f4761e0e31c045837875bc5b8cd4bb7160401a
Merge pull request #402 from einhverfr/master

Duplicate user handling in setup.pl