valgrind reports a problem in ext/session/tests/session_decode_error2.phpt

Just a minor heads up. There seem to be a problem in the unserializer discovered with help of ext/session/tests/session_decode_error2.phpt (see below). I don't know this part of the code good enough to fix it, so whoever does - please take a look at it. Thanks. ==18510== Invalid read of size 1

==18510==    at 0x7C16C2: php_var_unserialize (var_unserializer.c:514)
==18510==    by 0x7C3C04: process_nested_data (var_unserializer.re:281)
==18510==    by 0x7C2230: php_var_unserialize (var_unserializer.re:565)
==18510==    by 0x6483B9: ps_srlzr_decode_php (session.c:588)
==18510==    by 0x648B7A: php_session_decode (session.c:654)
==18510==    by 0x64E575: zif_session_decode (session.c:1802)
==18510==    by 0x8B2987: zend_do_fcall_common_helper_SPEC (zend_vm_execute.h:189)
==18510==    by 0x8B8100: ZEND_DO_FCALL_SPEC_CONST_HANDLER (zend_vm_execute.h:1399)
==18510==    by 0x8B2242: execute (zend_vm_execute.h:91)
==18510==    by 0x883710: zend_execute_scripts (zend.c:1192)
==18510==    by 0x80DF5E: php_execute_script (main.c:2077)
==18510==    by 0x924FC5: main (php_cli.c:1139)

==18510== Address 0x919d45e is 0 bytes after a block of size 14 alloc'd

==18510==    at 0x4C22DAB: malloc (vg_replace_malloc.c:207)
==18510==    by 0x85EA7F: _emalloc (zend_alloc.c:2281)
==18510==    by 0x85EFD7: _estrndup (zend_alloc.c:2423)
==18510==    by 0x78CF07: zif_substr (string.c:2213)
==18510==    by 0x8B2987: zend_do_fcall_common_helper_SPEC (zend_vm_execute.h:189)
==18510==    by 0x8B8100: ZEND_DO_FCALL_SPEC_CONST_HANDLER (zend_vm_execute.h:1399)
==18510==    by 0x8B2242: execute (zend_vm_execute.h:91)
==18510==    by 0x883710: zend_execute_scripts (zend.c:1192)
==18510==    by 0x80DF5E: php_execute_script (main.c:2077)
==18510==    by 0x924FC5: main (php_cli.c:1139)

-- Wbr, Antony Dovgal