Remove unnecessary distinct from query in Resource::find_fragments

[tommy-russoniello]

SELECT queries ordering by fields not being selected cannot be distinct in most newer versions of databases. This can potentially cause a database error such as one like this for MySQL:

Expression #1 of ORDER BY clause is not in SELECT list, references column 'some_database.users.name' which is not in SELECT list; this is incompatible with DISTINCT

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[lgebhardt]

Looks good to me