When I'm trying to restore DB backup, I'm getting assertion failure message. Backup has been made by mongobackup ver. 2.4.4 (in production env) and I've tried to restore both using 2.4.4 and 2.4.6. In all cases I'm getting following error messages, after which mongorestore stops working (flags: --journal --directoryperdb --dbpath):

MongoDB 2.4.4:
Fri Oct 18 10:21:15.841 [tools] Assertion failure amt == (size_t)( size - 4 ) src/mongo/tools/tool.cpp 508
0xdd7561 0xd99ebd 0xd8f56a 0x6e3606 0x6e2a5b 0x6e2a5b 0x6e6d6c 0xd8e278 0xd93475 0x6cbf77 0x7f1c41aaed85 0x6cbde9
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo15printStackTraceERSo+0x21) [0xdd7561]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo12verifyFailedEPKcS1_j+0xfd) [0xd99ebd]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo8BSONTool11processFileERKN5boost11filesystem34pathE+0x78a) [0xd8f56a]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0xf36) [0x6e3606]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0x38b) [0x6e2a5b]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0x38b) [0x6e2a5b]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore5doRunEv+0xc7c) [0x6e6d6c]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo8BSONTool3runEv+0x458) [0xd8e278]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo4Tool4mainEiPPc+0x13d5) [0xd93475]
/home/pawel/bin/mongo/bin/mongorestore(main+0x37) [0x6cbf77]
/lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1c41aaed85]
/home/pawel/bin/mongo/bin/mongorestore(__gxx_personality_v0+0x459) [0x6cbde9]
assertion: 0 assertion src/mongo/tools/tool.cpp:508

MongoDB 2.4.6:
Fri Oct 18 11:16:18.912 [tools] Assertion failure amt == (size_t)( size - 4 ) src/mongo/tools/tool.cpp 508
0xde30f1 0xda58ed 0xd9d71a 0x6e4816 0x6e3c6b 0x6e3c6b 0x6e7f7c 0xd99cc8 0xd9fa5e 0x6cd187 0x7f7a00fe6d85 0x6ccff9
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo15printStackTraceERSo+0x21) [0xde30f1]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo12verifyFailedEPKcS1_j+0xfd) [0xda58ed]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo8BSONTool11processFileERKN5boost11filesystem34pathE+0x78a) [0xd9d71a]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0xf36) [0x6e4816]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0x38b) [0x6e3c6b]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore9drillDownEN5boost11filesystem34pathEbbbb+0x38b) [0x6e3c6b]
/home/pawel/bin/mongo/bin/mongorestore(_ZN7Restore5doRunEv+0xc7c) [0x6e7f7c]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo8BSONTool3runEv+0x458) [0xd99cc8]
/home/pawel/bin/mongo/bin/mongorestore(_ZN5mongo4Tool4mainEiPPc+0x13de) [0xd9fa5e]
/home/pawel/bin/mongo/bin/mongorestore(main+0x37) [0x6cd187]
/lib64/libc.so.6(__libc_start_main+0xf5) [0x7f7a00fe6d85]
/home/pawel/bin/mongo/bin/mongorestore(__gxx_personality_v0+0x461) [0x6ccff9]
assertion: 0 assertion src/mongo/tools/tool.cpp:508