busybox cat and syscall 239

[SaphireLattice]

Busybox's (from archlinux i686) cat (and tar) fails when run (even without args):

[16:34:20.8233626] (II) We're a fork child.
[16:34:20.8243627] (II) PID: 82
[16:34:20.8243627] (II) Restoring TLS context...
[16:34:20.8243627] (II) user entry 1 value 0x0811f680
[16:34:20.8243627] (II) kernel entry 2 value 0x7ef60000
[16:34:20.8243627] (II) kernel entry 3 value 0x08104da7
[16:34:20.8243627] (II) kernel entry 4 value 0x00000003
[16:34:20.8243627] (II) kernel entry 5 value 0x0811f680
[16:34:20.8243627] (II) kernel entry 6 value 0x7dfe0890
[16:34:20.8243627] (II) kernel entry 7 value 0x0076ff80
[16:34:20.8243627] (II) kernel entry 8 value 0x00000000
[16:34:20.8243627] (II) kernel entry 9 value 0x00000000
[16:34:20.8243627] (II) Initializing dbt subsystem...
[16:34:20.8243627] (II) dbt subsystem initialized.
[16:34:20.8243627] (II) dbt: Restoring fork context, (original: pc: 080dd068, sp: 0076f844)
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 080dd068 (page 000080dd)
[16:34:20.8243627] (II) Detached block 0x0000080d successfully loaded.
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 080e3547 (page 000080e3)
[16:34:20.8243627] (II) Detached block 0x0000080e successfully loaded.
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 08048740 (page 00008048)
[16:34:20.8243627] (II) Detached block 0x00000804 successfully loaded.
[16:34:20.8243627] (II) IP: 0x7dfe01de
[16:34:20.8243627] (II) Handling page fault at address 0811f680 (page 0000811f)
[16:34:20.8243627] (II) Detached block 0x00000811 successfully loaded.
[16:34:20.8243627] (II) gettid(): 82
[16:34:20.8243627] (II) IP: 0x7dfe0217
[16:34:20.8243627] (II) Handling page fault at address 0811f710 (page 0000811f)
[16:34:20.8243627] (II) We're the only owner.
[16:34:20.8243627] (II) CoW section 00000811 successfully duplicated.
[16:34:20.8243627] (II) rt_sigprocmask(2, 0x0076f868, 0x00000000)
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 08090102 (page 00008090)
[16:34:20.8243627] (II) Detached block 0x00000809 successfully loaded.
[16:34:20.8243627] (II) IP: 0x7dfe03d9
[16:34:20.8243627] (II) Handling page fault at address 081201d0 (page 00008120)
[16:34:20.8243627] (II) We're the only owner.
[16:34:20.8243627] (II) CoW section 00000812 successfully duplicated.
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 0808df5f (page 0000808d)
[16:34:20.8243627] (II) Detached block 0x00000808 successfully loaded.
[16:34:20.8243627] (II) IP: 0x004028d2
[16:34:20.8243627] (II) Handling page fault at address 080f02b7 (page 000080f0)
[16:34:20.8243627] (II) Detached block 0x0000080f successfully loaded.
[16:34:20.8243627] (II) getpid(): 82
[16:34:20.8243627] (II) setpgid(0, 82)
[16:34:20.8243627] (II) ioctl(4, 5410, 76f8b4)
[16:34:20.8243627] (WW) Unsupported TIOCSPGRP: Do nothing.
[16:34:20.8243627] (II) rt_sigaction(20, 0076f7d0, 00000000)
[16:34:20.8243627] (II) rt_sigaction(22, 0076f7d0, 00000000)
[16:34:20.8243627] (II) rt_sigaction(2, 0076f7d0, 00000000)
[16:34:20.8243627] (II) rt_sigaction(15, 0076f7d0, 00000000)
[16:34:20.8243627] (II) rt_sigaction(3, 0076f7d0, 00000000)
[16:34:20.8243627] (II) IP: 0x7dfe0d5d
[16:34:20.8243627] (II) Handling page fault at address 081051a6 (page 00008105)
[16:34:20.8243627] (II) Detached block 0x00000810 successfully loaded.
[16:34:20.8243627] (II) IP: 0x7dfe1c00
[16:34:20.8243627] (II) Handling page fault at address 6ffa0033 (page 0006ffa0)
[16:34:20.8253627] (II) Detached block 0x00006ffa successfully loaded.
[16:34:20.8253627] (II) IP: 0x004028d2
[16:34:20.8253627] (II) Handling page fault at address 080b459c (page 000080b4)
[16:34:20.8253627] (II) Detached block 0x0000080b successfully loaded.
[16:34:20.8253627] (EE) FATAL: Unimplemented syscall: 239

Windows 7 Pro SP1 x64