BUG: work around pandas issue 12622. Close #787
BUG: work around pandas issue 12622. Close #787

cloudera/ibis,wesm/ibis,mariusvniekerk/ibis,deepfield/ibis,cloudera/ibis,cloudera/ibis,deepfield/ibis,ibis-project/ibis,cpcloud/ibis,deepfield/ibis,cpcloud/ibis,wesm/ibis,mariusvniekerk/ibis,ibis-project/ibis,ibis-project/ibis,cpcloud/ibis,cpcloud/ibis,wesm/ibis,deepfield/ibis,ibis-project/ibis,mariusvniekerk/ibis,mariusvniekerk/ibis