Problem:
As reported in logs

Sat Mar 19 04:21:44 [conn224] splitVector doing another cycle because of force, keyCount now: 1678740
Sat Mar 19 04:21:45 Got signal: 11 (Segmentation fault).

Sat Mar 19 04:21:45 Backtrace:
0x8a5359 0x7fad81c02af0 0x89053d 0x893356 0x7dc5f0 0x7ddb21 0x645565 0x64addc 0x757f15 0x75a440 0x8a617e 0x8b92d0 0x7fad827069ca 0x7fad81cb570d
/usr/bin/mongod(_ZN5mongo10abruptQuitEi+0x399) [0x8a5359]
/lib/libc.so.6(+0x33af0) [0x7fad81c02af0]
/usr/bin/mongod(_ZNK5mongo11BtreeCursor9prettyKeyERKNS_7BSONObjE+0x1d) [0x89053d]
/usr/bin/mongod(_ZN5mongo11SplitVector3runERKSsRNS_7BSONObjERSsRNS_14BSONObjBuilderEb+0x2996) [0x893356]
/usr/bin/mongod(_ZN5mongo11execCommandEPNS_7CommandERNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x9a0) [0x7dc5f0]
/usr/bin/mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x831) [0x7ddb21]
/usr/bin/mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x35) [0x645565]
/usr/bin/mongod(ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1+0x31ac) [0x64addc]
/usr/bin/mongod() [0x757f15]
/usr/bin/mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_8SockAddrE+0x5b0) [0x75a440]
/usr/bin/mongod(_ZN5mongo10connThreadEPNS_13MessagingPortE+0x21e) [0x8a617e]
/usr/bin/mongod(thread_proxy+0x80) [0x8b92d0]
/lib/libpthread.so.0(+0x69ca) [0x7fad827069ca]
/lib/libc.so.6(clone+0x6d) [0x7fad81cb570d]

Sat Mar 19 04:21:45 dbexit:
Sat Mar 19 04:21:45 [conn224] shutdown: going to close listening sockets...
Sat Mar 19 04:21:45 [conn224] closing listening socket: 6
Sat Mar 19 04:21:45 [conn224] closing listening socket: 7
Sat Mar 19 04:21:45 [conn224] closing listening socket: 8
Sat Mar 19 04:21:45 [conn224] closing listening socket: 9
Sat Mar 19 04:21:45 [conn224] removing socket file: /tmp/mongodb-27017.sock
Sat Mar 19 04:21:45 [conn224] removing socket file: /tmp/mongodb-28017.sock
Sat Mar 19 04:21:45 [conn224] shutdown: going to flush diaglog...
Sat Mar 19 04:21:45 [conn224] shutdown: going to close sockets...
Sat Mar 19 04:21:45 [conn224] shutdown: waiting for fs preallocator...
Sat Mar 19 04:21:45 [conn224] shutdown: closing all files...
Sat Mar 19 04:21:45 [conn292] end connection 10.120.9.214:45651
Sat Mar 19 04:21:45 [conn293] end connection 10.120.9.214:45652
Sat Mar 19 04:21:46 [conn4] end connection 10.122.99.3:40790
Sat Mar 19 04:21:46 [conn3] end connection 10.120.119.58:57884
52/78 66%
Sat Mar 19 04:21:47 [conn270] end connection 10.253.171.65:37712
71/78 91%
Sat Mar 19 04:21:49 closeAllFiles() finished
Sat Mar 19 04:21:49 [conn224] shutdown: removing fs lock...
Sat Mar 19 04:21:49 dbexit: really exiting now
Sat Mar 19 04:21:49 ERROR: Client::~Client _context should be null but is not; client:conn

Reproduce:
Not clear:

Workaround:
Startup the DB, it will re-join the set