Use default modifier when no relative path found

Author: nickspoons

autoload/OmniSharp/util.vim

@@ -294,6 +294,7 @@ function! OmniSharp#util#TranslatePathForClient(filename) abort
     if common !=# s:dir_separator
       return result . substitute(filename, common . s:dir_separator, '', '')
     endif
+    let modifiers = ':p'
   endif
 
   return fnamemodify(filename, modifiers)