When copying a selection in an image, sometimes it crashes (sometimes it doesn't).

GIMP 2.8.18 from https://www.gimp.org/downloads/ on macOS 10.12.1.

Crash dialog:
 

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000018
Exception Note:        EXC_CORPSE_NOTIFY

Termination Signal:    Segmentation fault: 11
Termination Reason:    Namespace SIGNAL, Code 0xb
Terminating Process:   exc handler [0]

VM Regions Near 0x18:
--> 
    __TEXT                 0000000100000000-00000001006b9000 [ 6884K] r-x/rwx SM=COW  /Applications/GIMP.app/Contents/MacOS/GIMP-bin

Application Specific Information:
objc_msgSend() selector name: retain


Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib               	0x00007fff956f0b5d objc_msgSend + 29
1   libgtk-quartz-2.0.0.dylib     	0x0000000100dc101e gtk_clipboard_set_contents + 318
2   libgtk-quartz-2.0.0.dylib     	0x0000000100dc13b6 gtk_clipboard_set_with_owner + 454
3   GIMP-bin                      	0x000000010017a3db gimp_clipboard_set_buffer + 571
4   GIMP-bin                      	0x00000001000118c0 gui_global_buffer_changed + 32
5   libgobject-2.0.0.dylib        	0x00000001019466cc g_cclosure_marshal_VOID__VOID + 236
6   libgobject-2.0.0.dylib        	0x00000001019421ca g_closure_invoke + 522
7   libgobject-2.0.0.dylib        	0x0000000101966d0d signal_emit_unlocked_R + 1693
8   libgobject-2.0.0.dylib        	0x0000000101968bed g_signal_emit_valist + 6141
9   libgobject-2.0.0.dylib        	0x0000000101969594 g_signal_emit + 356
10  GIMP-bin                      	0x0000000100366963 gimp_set_global_buffer + 531
11  GIMP-bin                      	0x000000010036a374 gimp_edit_copy + 868
12  GIMP-bin                      	0x000000010002b9a8 edit_copy_cmd_callback + 136
13  libgobject-2.0.0.dylib        	0x00000001019466cc g_cclosure_marshal_VOID__VOID + 236
14  libgobject-2.0.0.dylib        	0x00000001019421ca g_closure_invoke + 522
15  libgobject-2.0.0.dylib        	0x0000000101966d0d signal_emit_unlocked_R + 1693
16  libgobject-2.0.0.dylib        	0x0000000101968bed g_signal_emit_valist + 6141
17  libgobject-2.0.0.dylib        	0x0000000101969594 g_signal_emit + 356
18  libgtk-quartz-2.0.0.dylib     	0x0000000100a3aefd _gtk_action_emit_activate + 109
19  libgtk-quartz-2.0.0.dylib     	0x0000000100a3eb34 closure_accel_activate + 116
20  libgobject-2.0.0.dylib        	0x00000001019421ca g_closure_invoke + 522
21  libgobject-2.0.0.dylib        	0x0000000101966d0d signal_emit_unlocked_R + 1693
22  libgobject-2.0.0.dylib        	0x0000000101968c97 g_signal_emit_valist + 6311
23  libgobject-2.0.0.dylib        	0x0000000101969594 g_signal_emit + 356
24  libgtk-quartz-2.0.0.dylib     	0x0000000100a33120 gtk_accel_group_activate + 448
25  libgtk-quartz-2.0.0.dylib     	0x0000000100a33282 gtk_accel_groups_activate + 338
26  libgtk-quartz-2.0.0.dylib     	0x0000000100db89dc gtk_window_activate_key + 748
27  GIMP-bin                      	0x00000001002818f2 gimp_window_key_press_event + 866
28  libgtk-quartz-2.0.0.dylib     	0x0000000100b9b6ee _gtk_marshal_BOOLEAN__BOXED + 334
29  libgobject-2.0.0.dylib        	0x0000000101942cd8 g_type_class_meta_marshal + 120
30  libgobject-2.0.0.dylib        	0x00000001019421ca g_closure_invoke + 522
31  libgobject-2.0.0.dylib        	0x0000000101966edb signal_emit_unlocked_R + 2155
32  libgobject-2.0.0.dylib        	0x0000000101968c97 g_signal_emit_valist + 6311
33  libgobject-2.0.0.dylib        	0x0000000101969594 g_signal_emit + 356
34  libgtk-quartz-2.0.0.dylib     	0x0000000100d9aa9e gtk_widget_event_internal + 718
35  libgtk-quartz-2.0.0.dylib     	0x0000000100d9a7c4 gtk_widget_event + 340
36  libgtk-quartz-2.0.0.dylib     	0x0000000100b96ff5 gtk_propagate_event + 693
37  libgtk-quartz-2.0.0.dylib     	0x0000000100b96778 gtk_main_do_event + 1320
38  libgdk-quartz-2.0.0.dylib     	0x00000001010e0e94 gdk_event_dispatch + 148
39  libglib-2.0.0.dylib           	0x00000001019fbc54 g_main_dispatch + 452
40  libglib-2.0.0.dylib           	0x00000001019fba73 g_main_context_dispatch + 51
41  libglib-2.0.0.dylib           	0x00000001019fc050 g_main_context_iterate + 480
42  libglib-2.0.0.dylib           	0x00000001019fc562 g_main_loop_run + 578
43  GIMP-bin                      	0x000000010000a2d5 app_run + 1173
44  GIMP-bin                      	0x000000010000da07 main + 1255
45  GIMP-bin                      	0x0000000100009d74 start + 52