fix(tar): localize $i on options parse

Regression in 0fbb566

Author: scop

completions/tar

@@ -79,6 +79,7 @@ __gtar_parse_help_opt()
 
 __gtar_parse_help_line()
 {
+    local i
     local -a tmp
     while read -ra tmp; do
         for i in "${tmp[@]}"; do