Found crash on Chinese unicode“大东宝马”，any one found it？

[fei jay]

#0 0x00007fb7c2f7d418 in Tcl_UtfToUniChar () from libtcl8.6.so
#1 0x00007fb7c2f7ee1f in TclUtfToUCS4 () from libtcl8.6.so
#2 0x00007fb7c2f7f244 in Tcl_UtfToLower () from libtcl8.6.so
#3 0x00007fb7c2f1ebba in ?? () from libtcl8.6.so
#4 0x00007fb7c2e84aa6 in TclNRRunCallbacks () from libtcl8.6.so
#5 0x00007fb7c2e86273 in TclEvalEx () from libtcl8.6.so
#6 0x00007fb7c2e868b3 in Tcl_EvalEx () from libtcl8.6.so
#7 0x00007fb7c2e868f5 in Tcl_Eval () from libtcl8.6.so