findAndModify can't handle {fields: {_id: 0}}

when using findAndModify and trying to remove the id field with {fields: {_id, 0}}
I'm getting an error:
uncaught exception: findAndModifyFailed failed: "exception: assertion db/../util/../util/../db/../bson/bsonobjbuilder.h:112"

To reproduce:
db.jobs.save( {
name: "Biz report",
inprogress: false, priority:1,
tasks : [ "run sales report", "email report" ]
} );

// without fields it works:
job = db.jobs.findAndModify({
query:

{name: "Biz report"}

,
sort :

{priority:-1}

,
update: {$set: {inprogress: true, started: new Date()}},
new: true
});

// works with fields too
job = db.jobs.findAndModify({
query:

{name: "Biz report"}

,
sort :

{priority:-1}

,
update: {$set: {inprogress: true, started: new Date()}},
fields:

{name: 1}

,
new: true
});

// find works when using {_id: 0} in fields:
db.jobs.find(

{name: "Biz report"}

,

{name:1, _id: 0}

)

// findAndModify fail when using {_id, 0} in fields:
job = db.jobs.findAndModify({
query:

{name: "Biz report"}

,
sort :

{priority:-1}

,
update: {$set: {inprogress: true, started: new Date()}},
fields:

{name: 1, _id: 0}

,
new: true
});