sorry - don't have exact steps to reproduce.
Was trying to set up replica sets. running random replica set commands on each server (both on the same local machine)
and then ran into this error. I think I had started them with the set name but without any seed hosts and then tried to manually st replica config with some replica details...

Saved off the state of the system (ie. binary and data files directory) so may be able to reproduce if we try to start up the servers again

[rs_sync] Sat Jul 24 15:44:01 TEMP Jul 24 15:35:38:1
[rs_sync] Sat Jul 24 15:44:01 TEMP Jul 24 15:21:41:1
[rs_sync] Sat Jul 24 15:44:01 replSet syncRollback 1
[initandlisten] Sat Jul 24 15:44:01 connection accepted from 127.0.0.1:53306 #4
[rs_sync] Sat Jul 24 15:44:01 replSet syncRollback 2 FindCommonPoint
[rs_sync] Sat Jul 24 15:44:01 replSet TEMP info syncRollback diff in end of log times : 837 seconds
[rs_sync] Sat Jul 24 15:44:01 Assertion: 10334:Invalid BSONObj spec size: 1157627904 (45000000) first element:KLv: ?type=61
0x100081028 0x10001b53b 0x1000b29cf 0x1000affa0 0x1001e5d73 0x1001e8b06 0x1001eb366 0x1001ec3f8 0x1001ecd52 0x10038b964 0x7fff825408b6 0x7fff82540769
0 mongod 0x0000000100081028 _ZN5mongo11msgassertedEiPKc + 456
1 mongod 0x000000010001b53b _ZN5mongo7BSONObj4initEPKcb + 443
2 mongod 0x00000001000b29cf _ZN5mongo14DBClientCursor4nextEv + 399
3 mongod 0x00000001000affa0 _ZN5mongo14DBClientCursor8nextSafeEv + 32
4 mongod 0x00000001001e5d73 _ZN5mongo27syncRollbackFindCommonPointEPNS_18DBClientConnectionES1_RNS_10HowToFixUpE + 2835
5 mongod 0x00000001001e8b06 _ZN5mongo11ReplSetImpl12syncRollbackERNS_11OplogReaderE + 1222
6 mongod 0x00000001001eb366 _ZN5mongo11ReplSetImpl8syncTailEv + 1462
7 mongod 0x00000001001ec3f8 _ZN5mongo11ReplSetImpl10syncThreadEv + 104
8 mongod 0x00000001001ecd52 _ZN5mongo15startSyncThreadEv + 210
9 mongod 0x000000010038b964 thread_proxy + 132
10 libSystem.B.dylib 0x00007fff825408b6 _pthread_start + 331
11 libSystem.B.dylib 0x00007fff82540769 thread_start + 13
[rs_sync] Sat Jul 24 15:44:01 replSet syncRollback 2 exception 10334 Invalid BSONObj spec size: 1157627904 (45000000) first element:KLv: ?type=61 ; sleeping 1 min