Set 'notildeop' before preserving the case of the small camel

When 'tildeop' is set the command `normal! l~` doesn't work. So back up the option, set `notildeop`, and restore it afterwards.

Author: MageJohn

autoload/textobj/variable_segment.vim

@@ -38,7 +38,10 @@ function! s:select_a()
         if start_column - 2 <= word_start ||
          \ getline(start_line)[:start_column - 2] =~# '^_*$'
             call setpos('.', end_position)
+            let l:tildeop = &tildeop
+            set notildeop
             normal! l~
+            let &tildeop = l:tildeop
         endif
     endif