Ruby 777

With pre-2.6 servers, the bulk API has an edge case around documents with non-ObjectID _id fields.  This pull request offers a workaround for the issue.
Ruby is different from python here so won't throw

Ruby:
    irb(main):001:0> hash = {}
    => {}
    irb(main):002:0> hash[:q]
    => nil

python:

    >>> dict = {}
    >>> dict['q']
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    KeyError: 'q'