fix(dos): remove incorrect CR

Fixes #875

lua/gitsigns/diff_int.lua

@@ -69,8 +69,8 @@ function M.run_diff(fa, fb, diff_algo, indent_heuristic, linematch)
     run_diff0 = run_diff_xdl
   end
 
-  local a = vim.tbl_isempty(fa) and '' or table.concat(fa, '\n')
-  local b = vim.tbl_isempty(fb) and '' or table.concat(fb, '\n')
+  local a = table.concat(fa, '\n')
+  local b = table.concat(fb, '\n')
 
   local results = run_diff0(a, b, diff_algo, indent_heuristic, linematch)
 

lua/gitsigns/util.lua

@@ -49,13 +49,19 @@ function M.buf_lines(bufnr)
   -- nvim_buf_get_lines strips carriage returns if fileformat==dos
   local buftext = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
 
-  if vim.bo[bufnr].fileformat == 'dos' then
-    for i = 1, #buftext do
+  local dos = vim.bo[bufnr].fileformat == 'dos'
+
+  if dos then
+    for i = 1, #buftext - 1 do
       buftext[i] = buftext[i] .. '\r'
     end
   end
 
   if vim.bo[bufnr].endofline then
+    -- Add CR to the last line
+    if dos then
+      buftext[#buftext] = buftext[#buftext] .. '\r'
+    end
     buftext[#buftext + 1] = ''
   end