Vectorification fails during eval

[lewfish]

I ran the Vegas example in test mode and it crashed. This was when running with the following diff

diff --git a/spacenet/vegas.py b/spacenet/vegas.py
index b6c8aa5..30dfec6 100644
--- a/spacenet/vegas.py
+++ b/spacenet/vegas.py
@@ -125,6 +125,11 @@ def build_scene(task, spacenet_config, id, channel_order=None, vector_tile_optio
         label_source = rv.LabelSourceConfig.builder(rv.SEMANTIC_SEGMENTATION) \
             .with_raster_source(label_raster_source) \
             .build()
+
+        label_store = rv.LabelStoreConfig.builder(rv.SEMANTIC_SEGMENTATION_RASTER) \
+            .with_vector_output([{'mode': 'polygons', 'class_id': 1}]) \
+            .build()
+
     elif task.task_type == rv.CHIP_CLASSIFICATION:
         label_source = rv.LabelSourceConfig.builder(rv.CHIP_CLASSIFICATION) \
                                            .with_vector_source(vector_source) \
@@ -144,6 +149,7 @@ def build_scene(task, spacenet_config, id, channel_order=None, vector_tile_optio
                           .with_id(id) \
                           .with_raster_source(raster_source) \
                           .with_label_source(label_source) \
+                          .with_label_store(label_store) \
                           .build()

     return scene

root@65ee5b0edbad:/opt/src# rastervision run local -e spacenet.vegas     -a test True     -a use_remote_data False     -a root_uri ${ROOT_URI}     -a target buildings     -a task_type semantic_segmentation
None
Ensuring input files exist    [####################################]  100%
Checking for existing output  [####################################]  100%
Saving command configuration to /opt/data/spacenet/vegas/eval/buildings_semantic_segmentation/command-config.json...
Running evaluator: SemanticSegmentationEvaluator...
2019-01-16 19:21:25:rastervision.evaluation.semantic_segmentation_evaluator: INFO - Computing evaluation for scene 1332...
2019-01-16 19:21:25:rastervision.evaluation.semantic_segmentation_evaluator: INFO - Computing evaluation for scene 2530...
TopologyException: Input geom 1 is invalid: Ring Self-intersection at or near point -115.2387621 36.218666699899998 at -115.2387621 36.218666699899998
Traceback (most recent call last):
  File "/usr/lib/python3.5/runpy.py", line 184, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/opt/src/rastervision/__main__.py", line 17, in <module>
    rv.main()
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.5/dist-packages/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/opt/src/rastervision/cli/main.py", line 253, in run_command
    rv.runner.CommandRunner.run(command_config_uri)
  File "/opt/src/rastervision/runner/command_runner.py", line 11, in run
    CommandRunner.run_from_proto(msg)
  File "/opt/src/rastervision/runner/command_runner.py", line 17, in run_from_proto
    command.run()
  File "/opt/src/rastervision/command/eval_command.py", line 24, in run
    evaluator.process(scenes, tmp_dir)
  File "/opt/src/rastervision/evaluation/semantic_segmentation_evaluator.py", line 54, in process
    gt_geojson, pred_geojson_local, mode, class_id)
  File "/opt/src/rastervision/evaluation/semantic_segmentation_evaluation.py", line 130, in compute_vector
    results = score.spacenet(predictions, ground_truth)
  File "/usr/local/lib/python3.5/dist-packages/mask_to_polygons/processing/score.py", line 47, in spacenet
    scores = list(map(lambda a: iou(a, pred), results))
  File "/usr/local/lib/python3.5/dist-packages/mask_to_polygons/processing/score.py", line 47, in <lambda>
    scores = list(map(lambda a: iou(a, pred), results))
  File "/usr/local/lib/python3.5/dist-packages/mask_to_polygons/processing/score.py", line 35, in iou
    a_and_b = a.intersection(b).area
  File "/usr/local/lib/python3.5/dist-packages/shapely/geometry/base.py", line 620, in intersection
    return geom_factory(self.impl['intersection'](self, other))
  File "/usr/local/lib/python3.5/dist-packages/shapely/topology.py", line 70, in __call__
    self._check_topology(err, this, other)
  File "/usr/local/lib/python3.5/dist-packages/shapely/topology.py", line 38, in _check_topology
    self.fn.__name__, repr(geom)))
shapely.errors.TopologicalError: The operation 'GEOSIntersection_r' could not be performed. Likely cause is invalidity of the geometry <shapely.geometry.polygon.Polygon object at 0x7f21f68fcfd0>