Fix race condition with ordinal scale
Fix race condition with ordinal scale

bloomberg/bqplot,SylvainCorlay/bqplot,dmadeka/bqplot,ssunkara1/bqplot,dmadeka/bqplot,ChakriCherukuri/bqplot,SylvainCorlay/bqplot,SylvainCorlay/bqplot,bloomberg/bqplot,ssunkara1/bqplot,ChakriCherukuri/bqplot,bloomberg/bqplot,ChakriCherukuri/bqplot