[gimp/gimp-2-10] Issue #1624 - Crashes when using Scissor Select Tool

[Ell <ell src gnome org>]

commit 387cc35c588867a52349839b049994c921ae8ef7
Author: Ell <ell_se yahoo com>
Date:   Fri Jun 15 08:08:13 2018 -0400

    Issue #1624 - Crashes when using Scissor Select Tool
    
    In GimpTool, always clear tool->drawable upon halting, even for
    tools that don't use it explicitly.
    
    GimpTool sets tool->drawable in its default button_press()
    implementation, and we potentially access it in
    gimp_display_shell_initialize_tool(), so failing to clear it when
    halting the tool may leave it as a dangling pointer, which can
    result in a segfault when trying to initialize the tool in the
    above function.  In particular, this happens with the iscissors
    tool.
    
    (cherry picked from commit 58c96f596e588a0d123d71fec282b207e7f45635)

 app/tools/gimptool.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/app/tools/gimptool.c b/app/tools/gimptool.c
index c4d3563cea..0d177cdb0b 100644
--- a/app/tools/gimptool.c
+++ b/app/tools/gimptool.c
@@ -329,7 +329,8 @@ gimp_tool_real_control (GimpTool       *tool,
       break;
 
     case GIMP_TOOL_ACTION_HALT:
-      tool->display = NULL;
+      tool->display  = NULL;
+      tool->drawable = NULL;
       break;
 
     case GIMP_TOOL_ACTION_COMMIT: