Arvados

For example, if I accidentally use "=" instead of "==" as the comparison operator, I get 0 items back without any indication that there is no way that filter could ever match:

# arv collection list -f '[["modified_at","=","2016-05-18T13:22:11Z"]]' -l 0
{
 "kind":"arvados#collectionList",
 "etag":"",
 "self_link":"",
 "offset":0,
 "limit":0,
 "items":[],
 "items_available":0
}
# arv collection list -f '[["modified_at","==","2016-05-18T13:22:11Z"]]' -l 0
{
 "kind":"arvados#collectionList",
 "etag":"",
 "self_link":"",
 "offset":0,
 "limit":0,
 "items":[],
 "items_available":2597859
}