vim-patch:8.1.0303: line2byte() is wrong for last line with 'noeol'

Problem:    line2byte() is wrong for last line with 'noeol' and 'nofixeol'.
Solution:   Fix off-by-one error. (Shane Harper, closes vim/vim#3351)
c26f7c6053

src/nvim/testdir/test_functions.vim

@@ -701,6 +701,7 @@ endfunc
 
 func Test_byte2line_line2byte()
   new
+  set endofline
   call setline(1, ['a', 'bc', 'd'])
 
   set fileformat=unix
@@ -721,7 +722,16 @@ func Test_byte2line_line2byte()
   call assert_equal([-1, -1, 1, 4, 8, 11, -1],
   \                 map(range(-1, 5), 'line2byte(v:val)'))
 
-  set fileformat&
+  bw!
+  set noendofline nofixendofline
+  normal a-
+  for ff in ["unix", "mac", "dos"]
+    let &fileformat = ff
+    call assert_equal(1, line2byte(1))
+    call assert_equal(2, line2byte(2))  " line2byte(line("$") + 1) is the buffer size plus one (as per :help line2byte).
+  endfor
+
+  set endofline& fixendofline& fileformat&
   bw!
 endfunc