edit_dataset_metadata replace bug

[arielg96]

Even though I set "replace" = True. I get:

You may not add data to a field that already has data and does not allow multiples. Use is_replace=true to replace existing data.

I even printed out the params with the result:{'replace': True}

[pdurbin]

Hmm, I wonder if this would be fixed by this PR:

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