fix(_init_completion): update redirection pattern

Author: akinomyoga

bash_completion

@@ -1003,7 +1003,7 @@ _init_completion()
     done
 
     COMPREPLY=()
-    local redir="@(?([0-9])<|?([0-9&])>?(>)|>&)"
+    local redir='@(?(+([0-9])|{[a-zA-Z_]*([a-zA-Z_0-9])})@(>?([>|&])|<?([>&])|<<?([-<]))|&>?(>))'
     _get_comp_words_by_ref -n "$exclude<>&" cur prev words cword
 
     # Complete variable names.