From bca3e864551368c8c09b1361dc8aaa9cdb03e09b Mon Sep 17 00:00:00 2001
From: bubnikv <bubnikv@gmail.com>
Date: Tue, 4 Feb 2020 17:46:23 +0100
Subject: [PATCH] Fixed invalidation of FDM back end if a custom per layer
 extruder change is added or removed.

---
 src/libslic3r/Print.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index 2e6d5f8af..3f8fd9b40 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -494,7 +494,7 @@ static bool custom_per_printz_gcodes_tool_changes_differ(const std::vector<Custo
 {
 	auto it_a = va.begin();
 	auto it_b = vb.begin();
-	while (it_a != va.end() && it_b != vb.end()) {
+	while (it_a != va.end() || it_b != vb.end()) {
 		if (it_a != va.end() && it_a->gcode != ToolChangeCode) {
 			// Skip any CustomGCode items, which are not tool changes.
 			++ it_a;