Description:
------------
Segfault that happens since revision 318671 (Fixing #60139).

Test script:
---------------
For now, I can only repeat this with phpunit if putting 4-5 tests together, not a single test script is able to reproduce it.
I can take some time if it is really required.

Expected result:
----------------
No segfault :)

Actual result:
--------------
Program received signal SIGSEGV, Segmentation fault.
0x00000000012433a0 in ?? ()
(gdb) bt
#0  0x00000000012433a0 in ?? ()
#1  0x0000000000904d5e in zval_mark_grey (pz=0x2d7add0) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_gc.c:395
#2  0x0000000000904e1c in zval_mark_grey (pz=0x2d7add0) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_gc.c:407
#3  0x00000000009051d2 in gc_mark_roots () at /home/patrick.allaert/Projets/php-
src/Zend/zend_gc.c:501
#4  0x0000000000905d4d in gc_collect_cycles () at 
/home/patrick.allaert/Projets/php-src/Zend/zend_gc.c:793
#5  0x00000000009043e1 in gc_zval_possible_root (zv=0x2d818c0) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_gc.c:166
#6  0x00000000009552bc in gc_zval_check_possible_root 
(execute_data=0x7ffff7d78a78) at /home/patrick.allaert/Projets/php-
src/Zend/zend_gc.h:183
#7  zend_pzval_unlock_func (execute_data=0x7ffff7d78a78) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_execute.c:81
#8  _get_zval_ptr_var (execute_data=0x7ffff7d78a78) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_execute.c:184
#9  ZEND_FE_RESET_SPEC_VAR_HANDLER (execute_data=0x7ffff7d78a78) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_vm_execute.h:11392
#10 0x000000000091a2f6 in execute (op_array=0x2a4b0c0) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_vm_execute.h:410
#11 0x00000000008c8e85 in zend_call_function (fci=0x7fffffffa0d0, 
fci_cache=0x7fffffffa060) at /home/patrick.allaert/Projets/php-
src/Zend/zend_execute_API.c:958
#12 0x00000000008fb059 in zend_call_method (object_pp=0x7fffffffa188, 
obj_ce=0x28bccb8, fn_proxy=0x28bcdf0, function_name=0xe6b20a "__get", 
function_name_len=5, retval_ptr_ptr=0x7fffffffa198, param_count=1, 
arg1=0x2d6c100, arg2=0x0)
    at /home/patrick.allaert/Projets/php-src/Zend/zend_interfaces.c:97
#13 0x000000000090a3ca in zend_std_call_getter (object=0x2d3cae0, 
member=0x2d6c100) at /home/patrick.allaert/Projets/php-
src/Zend/zend_object_handlers.c:147
#14 0x000000000090c342 in zend_std_read_property (object=0x2d3cae0, 
member=0x2993810, type=0, key=0x2993810) at /home/patrick.allaert/Projets/php-
src/Zend/zend_object_handlers.c:448
#15 0x0000000000965b0c in zend_fetch_property_address_read_helper_SPEC_VAR_CONST 
(execute_data=0x7ffff7d76240) at /home/patrick.allaert/Projets/php-
src/Zend/zend_vm_execute.h:12868
#16 0x0000000000967a06 in ZEND_FETCH_OBJ_FUNC_ARG_SPEC_VAR_CONST_HANDLER 
(execute_data=0x7ffff7d76240) at /home/patrick.allaert/Projets/php-
src/Zend/zend_vm_execute.h:13045
#17 0x000000000091a2f6 in execute (op_array=0x2a87908) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_vm_execute.h:410
#18 0x00000000008c8e85 in zend_call_function (fci=0x7fffffffaae0, 
fci_cache=0x7fffffffaab0) at /home/patrick.allaert/Projets/php-
src/Zend/zend_execute_API.c:958
#19 0x00000000006da9ae in zim_reflection_method_invokeArgs (ht=2, 
return_value=0x2c73570, return_value_ptr=0x0, this_ptr=0x2c73498, 
return_value_used=1) at /home/patrick.allaert/Projets/php-
src/ext/reflection/php_reflection.c:2924
#20 0x000000000091b979 in zend_do_fcall_common_helper_SPEC 
(execute_data=0x7ffff7d73a98) at /home/patrick.allaert/Projets/php-
src/Zend/zend_vm_execute.h:642
#21 0x000000000091c84a in ZEND_DO_FCALL_BY_NAME_SPEC_HANDLER 
(execute_data=0x7ffff7d73a98) at /home/patrick.allaert/Projets/php-
src/Zend/zend_vm_execute.h:752
#22 0x000000000091a2f6 in execute (op_array=0x7ffff75df848) at 
/home/patrick.allaert/Projets/php-src/Zend/zend_vm_execute.h:410
#23 0x00000000008dc421 in zend_execute_scripts (type=8, retval=0x0, 
file_count=3) at /home/patrick.allaert/Projets/php-src/Zend/zend.c:1272
#24 0x0000000000852f48 in php_execute_script (primary_file=0x7fffffffd4a0) at 
/home/patrick.allaert/Projets/php-src/main/main.c:2414
#25 0x0000000000a25845 in do_cli (argc=6, argv=0x7fffffffd848) at 
/home/patrick.allaert/Projets/php-src/sapi/cli/php_cli.c:983
#26 0x0000000000a2675d in main (argc=6, argv=0x7fffffffd848) at 
/home/patrick.allaert/Projets/php-src/sapi/cli/php_cli.c:1356