ReplicaSet rollback should use slaveOk

Currently we are already querying secondaries but it will fail and get stuck in ROLLBACK state:

Th│Thu Aug 18 17:30:55 [rsSync] replSet syncing to: redbeard:10003
Th│Thu Aug 18 17:30:55 [rsSync] replSet our last op time written: Aug 18 17:26:03:1
Th│Thu Aug 18 17:30:55 [rsSync] replset source's GTE: Aug 18 17:28:08:1
Th│Thu Aug 18 17:30:55 [rsSync] replSet rollback 0
Th│Thu Aug 18 17:30:55 [rsSync] replSet ROLLBACK
Th│Thu Aug 18 17:30:55 [rsSync] replSet rollback 1
Th│Thu Aug 18 17:30:55 [rsSync] replSet rollback 2 FindCommonPoint
Th Thu Aug 18 17:30:55 [rsSync] replSet info rollback our last optime: Aug 18 17:26:03:1
03 Thu Aug 18 17:30:55 [rsSync] replSet info rollback their last optime: Aug 18 17:29:59:1
Th Thu Aug 18 17:30:55 [rsSync] replSet info rollback diff in end of log times: -236 seconds
Th Thu Aug 18 17:30:55 [rsSync] replSet rollback found matching events at Aug 18 17:20:12:1
Th Thu Aug 18 17:30:55 [rsSync] replSet rollback findcommonpoint scanned : 5
Th Thu Aug 18 17:30:55 [rsSync] replSet replSet rollback 3 fixup
Th Thu Aug 18 17:30:55 [rsSync] replSet rollback re-get objects: 13106 nextSafe():

{ $err: "not master and slaveok=false", code: 13435 }

Th Thu Aug 18 17:30:55 [rsSync] rollback couldn't re-get ns:test.foo _id:_id: 1.0 1/1
Th Thu Aug 18 17:30:55 [rsSync] replSet syncThread: 13106 nextSafe():

{ $err: "not master and slaveok=false", code: 13435 }

Th Thu Aug 18 17:31:06 [rsSync] replSet syncing to: redbeard:10003
Th Thu Aug 18 17:31:06 [rsSync] replSet our last op time written: Aug 18 17:26:03:1
Th Thu Aug 18 17:31:06 [rsSync] replset source's GTE: Aug 18 17:28:08:1
Th Thu Aug 18 17:31:06 [rsSync] replSet rollback 0
04 Thu Aug 18 17:31:06 [rsSync] replSet rollback 1
Th Thu Aug 18 17:31:06 [rsSync] replSet rollback 2 FindCommonPoint
Th Thu Aug 18 17:31:06 [rsSync] replSet rollback 2 error findcommonpoint waiting a while before trying again
Th Thu Aug 18 17:31:17 [rsSync] replSet syncing to: redbeard:10003
Th Thu Aug 18 17:31:17 [rsSync] replSet our last op time written: Aug 18 17:26:03:1
Th Thu Aug 18 17:31:17 [rsSync] replset source's GTE: Aug 18 17:28:08:1
Th Thu Aug 18 17:31:17 [rsSync] replSet rollback 0
Th Thu Aug 18 17:31:17 [rsSync] replSet rollback 1
Th Thu Aug 18 17:31:17 [rsSync] replSet rollback 2 FindCommonPoint
Th Thu Aug 18 17:31:17 [rsSync] replSet rollback 2 error findcommonpoint waiting a while before trying again
Th Thu Aug 18 17:31:20 [initandlisten] connection accepted from 127.0.0.1:49341 #8
Th Thu Aug 18 17:31:20 [initandlisten] warning: Stack size set to 768KB. We suggest 1MB
05 Thu Aug 18 17:31:28 [rsSync] replSet syncing to: redbeard:10003
Th Thu Aug 18 17:31:28 [rsSync] replSet our last op time written: Aug 18 17:26:03:1
Th Thu Aug 18 17:31:28 [rsSync] replset source's GTE: Aug 18 17:28:08:1
Th Thu Aug 18 17:31:28 [rsSync] replSet rollback 0
Th Thu Aug 18 17:31:28 [rsSync] replSet rollback 1
Th Thu Aug 18 17:31:28 [rsSync] replSet rollback 2 FindCommonPoint
Th Thu Aug 18 17:31:28 [rsSync] replSet rollback 2 error findcommonpoint waiting a while before trying again
Th Thu Aug 18 17:31:39 [rsSync] replSet syncing to: redbeard:10003
Th Thu Aug 18 17:31:39 [rsSync] replSet our last op time written: Aug 18 17:26:03:1

and so on...

I'll try to work up a jstest