patch 8.1.2140: "gk" and "gj" do not work correctly in number column

Problem:    "gk" and "gj" do not work correctly in number column.
Solution:   Allow for a negative "curswant". (Zach Wegner, closes #4969)
diff --git a/src/testdir/test_normal.vim b/src/testdir/test_normal.vim
index dcfa929..da9c004 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -2654,4 +2654,29 @@
   call assert_equal(95, virtcol('.'))
   bw!
   bw!
+
+  " needs 80 column new window
+  new
+  vert 80new
+  set number
+  set numberwidth=10
+  set cpoptions+=n
+  put =[repeat('0',90), repeat('1',90)]
+  norm! 075l
+  call assert_equal(76, col('.'))
+  norm! gk
+  call assert_equal(1, col('.'))
+  norm! gk
+  call assert_equal(76, col('.'))
+  norm! gk
+  call assert_equal(1, col('.'))
+  norm! gj
+  call assert_equal(76, col('.'))
+  norm! gj
+  call assert_equal(1, col('.'))
+  norm! gj
+  call assert_equal(76, col('.'))
+  bw!
+  bw!
+  set cpoptions& number& numberwidth&
 endfunc