There's a minor memory leak in the config code:
==43441== HEAP SUMMARY:
43441 in use at exit: 23,780 bytes in 20 blocks
43441 total heap usage: 4,019 allocs, 3,999 frees, 3,182,632 bytes allocated
43441
43441 250 bytes in 2 blocks are definitely lost in loss record 8 of 19
43441 at 0x5821D: calloc (in /usr/local/lib/valgrind/vgpreload_memcheck-x86-freebsd.so)
43441
43441 318 bytes in 1 blocks are definitely lost in loss record 16 of 19
43441 at 0x5821D: calloc (in /usr/local/lib/valgrind/vgpreload_memcheck-x86-freebsd.so)
43441 by 0x8067C68: __wt_calloc (os_alloc.c:37)
43441 by 0x80502F8: __wt_config_collapse (config.c:652)
43441 by 0x804E487: __session_create (api.c:138)
43441 by 0x804C578: wts_startup (wts.c:140)
43441 by 0x804B6D3: main (t.c:88)
43441
43441 LEAK SUMMARY:
43441 definitely lost: 568 bytes in 3 blocks
43441 indirectly lost: 0 bytes in 0 blocks
43441 possibly lost: 0 bytes in 0 blocks
43441 still reachable: 19,116 bytes in 16 blocks
43441 suppressed: 4,096 bytes in 1 blocks
43441 Reachable blocks (those to which a pointer was found) are not shown.
43441 To see them, rerun with: --leak-check=full --show-reachable=yes