within search fails when the bounding box crosses the anti-meridian on solr

• Tested with the latest Haystack release
• Tested with the current Haystack master branch

Expected behaviour

Doing a spatial search using within it takes the bottom left and top right which implies a bounding box. Doing a within search should give results within the bounding box.

Actual behaviour

No results since it's not doing a true bounding box but checking if points are between a min max latitude.

Steps to reproduce the behaviour

1. Index some results with points
2. Do a within query that has a bottom left in the left hemisphere and a top right in the right hemisphere

example bounds:

bounds=u'{"south":18.529137640349763,"west":175.8987575837,"north":53.046193148995805,"east":-88.12467991630001}'

Configuration

• Operating system version:
• Search engine version: solr 5
• Python version:
• Django version:
• Haystack version:

Misc

The code responsible is here:

        if within is not None:
            from haystack.utils.geo import generate_bounding_box

            kwargs.setdefault('fq', [])
            ((min_lat, min_lng), (max_lat, max_lng)) = generate_bounding_box(within['point_1'], within['point_2'])
            # Bounding boxes are min, min TO max, max. Solr's wiki was *NOT*
            # very clear on this.
            bbox = '%s:[%s,%s TO %s,%s]' % (within['field'], min_lat, min_lng, max_lat, max_lng)
            kwargs['fq'].append(bbox)

...

def generate_bounding_box(bottom_left, top_right):
    """
    Takes two opposite corners of a bounding box (order matters!) & generates
    a two-tuple of the correct coordinates for the bounding box.

    The two-tuple is in the form ``((min_lat, min_lng), (max_lat, max_lng))``.
    """
    west, lat_1 = bottom_left.get_coords()
    east, lat_2 = top_right.get_coords()
    min_lat, max_lat = min(lat_1, lat_2), max(lat_1, lat_2)
    return ((min_lat, west), (max_lat, east))

It looks like it's just looking for the min/max of latitude and not using the box that was passed in.

Start with the shown within-query handling and generate_bounding_box function, then reproduce the issue using the supplied anti-meridian bounds. Verify how the longitude range is constructed and confirm that a query crossing the anti-meridian returns points inside the bounding box.