su parses `'-g ' ghost` as `-g ghost`

[Jorge Aparicio]

whereas ogsu parses that as -g ' ' ghost

relevant test

sudo-rs/src/su/cli.rs

Lines 485 to 494 in d10d42f

 #[test] 
 fn short_flag_whitespace_positional_argument() { 
     let expected = SuOptions { 
         action: SuAction::Run, 
         group: vec![" ".to_string()], 
         user: "ghost".to_string(), 
         ..Default::default() 
     }; 
     assert_eq!(expected, parse(&["-g ", "ghost"])); 
 }