patch 8.0.1441: using ":undo 0" leaves undo in wrong statev8.0.1441

Problem:    Using ":undo 0" leaves undo in wrong state.
Solution:   Instead of searching for state 1 and go above, just use the start.
            (Ozaki Kiichi, closes #2595)

1 files changed, 44 insertions, 0 deletions

diff --git a/src/testdir/test_undo.vim b/src/testdir/test_undo.vim
index b7235867b..cc3cceb1a 100644
--- a/src/testdir/test_undo.vim
+++ b/src/testdir/test_undo.vim
@@ -359,3 +359,47 @@ func Test_undo_append()
   norm o
   quit
 endfunc
+
+func Test_undo_0()
+  new
+  set ul=100
+  normal i1
+  undo
+  normal i2
+  undo
+  normal i3
+
+  undo 0
+  let d = undotree()
+  call assert_equal('', getline(1))
+  call assert_equal(0, d.seq_cur)
+
+  redo
+  let d = undotree()
+  call assert_equal('3', getline(1))
+  call assert_equal(3, d.seq_cur)
+
+  undo 2
+  undo 0
+  let d = undotree()
+  call assert_equal('', getline(1))
+  call assert_equal(0, d.seq_cur)
+
+  redo
+  let d = undotree()
+  call assert_equal('2', getline(1))
+  call assert_equal(2, d.seq_cur)
+
+  undo 1
+  undo 0
+  let d = undotree()
+  call assert_equal('', getline(1))
+  call assert_equal(0, d.seq_cur)
+
+  redo
+  let d = undotree()
+  call assert_equal('1', getline(1))
+  call assert_equal(1, d.seq_cur)
+
+  bwipe!
+endfunc