cython: [BUG] segfault on pandas with 3.0a9

Building pandas master (which works with cython 0.29.x) with the 3.0a9 I’m getting a segfault in https://github.com/pandas-dev/pandas/blob/master/pandas/_libs/hashtable_func_helper.pxi.in#L110

lldb is pointing me towards a __Pyx_INCREF call:

frame #1: 0x000000011da6ef72 hashtable.cpython-39-darwin.so`__pyx_pw_6pandas_5_libs_9hashtable_73__pyx_fuse_12duplicated [inlined] __pyx_f_6pandas_5_libs_9hashtable_duplicated_object(__pyx_v_values=0x0000000000000000, __pyx_optional_args=<unavailable>) at hashtable.c:101383 [opt]
   101380	 *         raise ValueError('keep must be either "first", "last" or False')
   101381	 * 
   101382	 */
-> 101383	  __Pyx_INCREF(__pyx_v_keep);
   101384	  __pyx_t_2 = __pyx_v_keep;
   101385	  __pyx_t_9 = (__Pyx_PyUnicode_Equals(__pyx_t_2, __pyx_n_u_last, Py_NE)); if (unlikely((__pyx_t_9 < 0))) __PYX_ERR(3, 1504, __pyx_L1_error)
   101386	  if (__pyx_t_9) {

Not sure if this means anything, but sublimetext’s syntax highlighting seems to stop about 60k lines before this