New MUC does not show up in Chats list

It seems there's double-free caused by g_autofree for "history_since" chat attribute

(gdb) bt
#0  0x00007f9005c2a4a2 in free () at /usr/lib/libc.so.6
#1  0x00007f9006d5342f in  () at /usr/lib/libglib-2.0.so.0
#2  0x00007f9006d546a8 in g_hash_table_remove_all () at /usr/lib/libglib-2.0.so.0
#3  0x00007f9006d546ef in g_hash_table_destroy () at /usr/lib/libglib-2.0.so.0
#4  0x00007f90062536ce in purple_chat_destroy () at /usr/lib/libpurple.so.0
#5  0x000056478b1e102c in chatty_blist_chat_list_remove_buddy () at ../src/chatty-buddy-list.c:1008
#6  0x000056478b1ed218 in view_msg_list_cmd_delete (action=0x56478c6338a0, parameter=0x0, user_data=0x56478c6002b0) at ../src/chatty-popover-actions.c:55

   0x7f9006d53428:	mov    %r8,0x18(%rsp)
   0x7f9006d5342d:	callq  *%rdx
=> 0x7f9006d5342f:	mov    0x18(%rsp),%r8

r8             0x56478cab3e10      94865302699536

gdb) x/s 0x56478cab3e10
0x56478cab3e10:	"1970-01-01T00:00:01Z"

Suspected code:

void
chatty_conv_add_history_since_component (GHashTable *components,
                                         const char *account,
                                         const char *room){
  time_t mtime;
  struct tm * timeinfo;

  g_autofree gchar *iso_timestamp = g_malloc0(MAX_GMT_ISO_SIZE * sizeof(char));

  mtime = chatty_history_get_chat_last_message_time(account, room);
  mtime += 1; // Use the next epoch to exclude the last stored message(s)
  timeinfo = gmtime (&mtime);
  g_return_if_fail (strftime (iso_timestamp,
                              MAX_GMT_ISO_SIZE * sizeof(char),
                              "%Y-%m-%dT%H:%M:%SZ",
                              timeinfo));

  g_hash_table_steal (components, "history_since");
  g_hash_table_insert (components, "history_since", g_steal_pointer(&iso_timestamp));
}