fix(api) don't override parameters with new array
fix(api) don't override parameters with new array

The `normalize_nested_params()` function has a special case for the form
 `x[] = {1, 2, 3}`, but it simply replaced the `x` value with the `{1,
 2, 3}` array.  Existing tests have both `x[] = {1, 2, 3}` and
 `x[n] = y`.  Depending on iteration order, the result could be either
 `{1, 2, 3, n=y}` or just `{1, 2, 3}`, losing the `n` if it was
 overwritten by the array.

 This fix simply copies the contents of the array if the existing `x`
 value was already a table.

Kong/kong,Kong/kong,Kong/kong