Fix scrolling BufferView past empty lines

src/core/BufferView.cc

@@ -401,6 +401,7 @@ void BufferView::move_forward_to_screen_position(
         std::shared_ptr<Buffer::Iterator> line, int target_row_offset,
         bool allow_eol)
 {
+    *m_iterator = *line;
     for (auto it = horiz_iter(line); it.is_valid(); it++)
     {
         if ((allow_eol || (!it.is_eol())) &&

test/src/test_BufferView.cc

@@ -22,6 +22,21 @@ static std::shared_ptr<Buffer> buffer1()
     return std::make_shared<Buffer>((const uint8_t *)data, strlen(data));
 }
 
+static std::shared_ptr<Buffer> buffer2()
+{
+    static const char data[] =
+        "0\n"
+        "\n"
+        "2\n"
+        "3\n"
+        "4\n"
+        "\n"
+        "6\n"
+        "7\n"
+        "8\n";
+    return std::make_shared<Buffer>((const uint8_t *)data, strlen(data));
+}
+
 static std::shared_ptr<Buffer> buffer_empty()
 {
     return std::make_shared<Buffer>(nullptr, 0u);
@@ -698,3 +713,19 @@ TEST(BufferViewTest, shows_only_lines_in_buffer_if_fewer_lines_in_buffer_than_vi
     }
     EXPECT_EQ(13, count);
 }
+
+TEST(BufferViewTest, scrolls_past_empty_lines)
+{
+    auto b = buffer2();
+    auto iterator = b->add_cursor();
+    BufferView bv(b, iterator, Cwd);
+    bv.resize(10, 1);
+    bv.update();
+    EXPECT_EQ(0, LineNumber(iterator));
+    bv.scroll_view_down(3, false);
+    bv.update();
+    EXPECT_EQ(3, LineNumber(iterator));
+    bv.scroll_view_up(3, false);
+    bv.update();
+    EXPECT_EQ(0, LineNumber(iterator));
+}