I can reproduce this problem with Gentoo Hardened and 
gcc version 3.4.6 (Gentoo Hardened 3.4.6-r2 p1.6, ssp-3.4.6-1.0, pie-8.7.10)

when gdb-ing through the datetimemodule.c, and displaying the "tuple"
variable in time_strftime, I can see that the pointer gets modified by
the wrap_strftime call, resulting in Py_DECREF causing the segfault:
before wrap_strftime:
(gdb) x tuple
0xa8938f2c:	0x00000001
after wrap_strftime:
(gdb) x tuple
0x938f2c:	Cannot access memory at address 0x938f2c
thus executing
Py_DECREF(tuple)
results in the segfault.