From a1987e21d91fae2c8bb9050d8ad809ca604ae888 Mon Sep 17 00:00:00 2001
From: Quincy Morgan <2046746+quincylvania@users.noreply.github.com>
Date: Wed, 2 Sep 2020 11:07:09 -0400
Subject: [PATCH] Fix issue where undoing the second-to-first vertex of a way
 when drawing would undo to the initial state of the way (close #7772)

---
 modules/behavior/draw_way.js | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/modules/behavior/draw_way.js b/modules/behavior/draw_way.js
index 48eb679f6..56c7ef5ab 100644
--- a/modules/behavior/draw_way.js
+++ b/modules/behavior/draw_way.js
@@ -195,23 +195,23 @@ export function behaviorDrawWay(context, wayID, mode, startGraph) {
 
         var nextMode;
 
-        if (context.graph() === startGraph) { // we've undone back to the beginning
+        if (context.graph() === startGraph) {
+            // We've undone back to the initial state before we started drawing.
+            // Just exit the draw mode without undoing whatever we did before
+            // we entered the draw mode.
             nextMode = modeSelect(context, [wayID]);
         } else {
-            context.history()
-                .on('undone.draw', null);
-            // remove whatever segment was drawn previously
-            context.undo();
+            // The `undo` only removed the temporary edit, so here we have to
+            // manually undo to actually remove the last node we added. We can't
+            // use the `undo` function since the initial "add" graph doesn't have
+            // an annotation and so cannot be undone to.
+            context.pop(1);
 
-            if (context.graph() === startGraph) { // we've undone back to the beginning
-                nextMode = modeSelect(context, [wayID]);
-            } else {
-                // continue drawing
-                nextMode = mode;
-            }
+            // continue drawing
+            nextMode = mode;
         }
 
-        // clear the redo stack by adding and removing an edit
+        // clear the redo stack by adding and removing a blank edit
         context.perform(actionNoop());
         context.pop(1);