- avoid divide by zero with node progress

- write_crash_blend() was writing to the original path.

source/blender/blenkernel/intern/node.c

@@ -2465,7 +2465,7 @@ void ntreeCompositExecTree(bNodeTree *ntree, RenderData *rd, int do_preview)
 			node= getExecutableNode(ntree);
 			if(node) {
 				
-				if(ntree->progress)
+				if(ntree->progress && totnode)
 					ntree->progress(ntree->prh, (1.0 - curnode/(float)totnode));
 				if(ntree->stats_draw) {
 					char str[64];

source/blender/windowmanager/intern/wm_files.c

@@ -539,7 +539,7 @@ int write_crash_blend(void)
 	char path[FILE_MAX];
 	BLI_strncpy(path, G.sce, sizeof(path));
 	BLI_replace_extension(path, sizeof(path), "_crash.blend");
-	if(BLO_write_file(G.main, G.sce, G.fileflags, NULL, NULL)) {
+	if(BLO_write_file(G.main, path, G.fileflags, NULL, NULL)) {
 		printf("written: %s\n", path);
 		return 1;
 	}