patch 8.1.0682: text properties not adjusted when backspacing replaced text

Problem:    Text properties are not adjusted when backspacing replaced text.
Solution:   Keep text properties on text restored in replace mode.
diff --git a/src/testdir/test_textprop.vim b/src/testdir/test_textprop.vim
index 737ff20..d251237 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -145,6 +145,19 @@
   bwipe!
 endfunc
 
+func SetupOneLine()
+  call setline(1, 'xonex xtwoxx')
+  call AddPropTypes()
+  call prop_add(1, 2, {'length': 3, 'id': 11, 'type': 'one'})
+  call prop_add(1, 8, {'length': 3, 'id': 12, 'type': 'two'})
+  let expected = [
+	\ {'col': 2, 'length': 3, 'id': 11, 'type': 'one', 'start': 1, 'end': 1},
+	\ {'col': 8, 'length': 3, 'id': 12, 'type': 'two', 'start': 1, 'end': 1},
+	\]
+  call assert_equal(expected, prop_list(1))
+  return expected
+endfunc
+
 func Test_prop_add_remove_buf()
   new
   let bufnr = bufnr('')
@@ -180,15 +193,7 @@
 func Test_prop_backspace()
   new
   set bs=2
-  call setline(1, 'xonex xtwoxx')
-  call AddPropTypes()
-  call prop_add(1, 2, {'length': 3, 'id': 11, 'type': 'one'})
-  call prop_add(1, 8, {'length': 3, 'id': 12, 'type': 'two'})
-  let expected = [
-	\ {'col': 2, 'length': 3, 'id': 11, 'type': 'one', 'start': 1, 'end': 1},
-	\ {'col': 8, 'length': 3, 'id': 12, 'type': 'two', 'start': 1, 'end': 1},
-	\]
-  call assert_equal(expected, prop_list(1))
+  let expected = SetupOneLine() " 'xonex xtwoxx'
 
   exe "normal 0li\<BS>\<Esc>fxli\<BS>\<Esc>"
   call assert_equal('one xtwoxx', getline(1))
@@ -201,6 +206,32 @@
   set bs&
 endfunc
 
+func Test_prop_replace()
+  new
+  set bs=2
+  let expected = SetupOneLine() " 'xonex xtwoxx'
+
+  exe "normal 0Ryyy\<Esc>"
+  call assert_equal('yyyex xtwoxx', getline(1))
+  call assert_equal(expected, prop_list(1))
+
+  exe "normal ftRyy\<BS>"
+  call assert_equal('yyyex xywoxx', getline(1))
+  call assert_equal(expected, prop_list(1))
+
+  exe "normal 0fwRyy\<BS>"
+  call assert_equal('yyyex xyyoxx', getline(1))
+  call assert_equal(expected, prop_list(1))
+
+  exe "normal 0foRyy\<BS>\<BS>"
+  call assert_equal('yyyex xyyoxx', getline(1))
+  call assert_equal(expected, prop_list(1))
+
+  call DeletePropTypes()
+  bwipe!
+  set bs&
+endfunc
+
 func Test_prop_clear()
   new
   call AddPropTypes()