rename: save/restore tab/windows; not via new_buffer

Ref: https://github.com/davidhalter/jedi-vim/pull/364#discussion-diff-25785992

jedi_vim.py

@@ -428,10 +428,13 @@ def rename():
         vim_command('normal! diw')
         vim_command(':startinsert')
     else:
-        window_path = vim.current.buffer.name
         # reset autocommand
         vim_command('autocmd! jedi_rename InsertLeave')
 
+        # Save original window / tab.
+        saved_tab = int(vim_eval('tabpagenr()'))
+        saved_win = int(vim_eval('winnr()'))
+
         replace = vim_eval("expand('<cword>')")
         vim_command('normal! u')  # undo new word
         cursor = vim.current.window.cursor
@@ -458,9 +461,10 @@ def rename():
                 vim.current.window.cursor = r.start_pos
                 vim_command('normal! cw%s' % replace)
 
-            result = new_buffer(window_path)
-            if not result:
-                return
+            # Restore previous tab and window.
+            vim_command('tabnext {:d}'.format(saved_tab))
+            vim_command('{:d}wincmd w'.format(saved_win))
+
             vim.current.window.cursor = cursor
             echo_highlight('Jedi did %s renames!' % len(temp_rename))