builtin status: remove spurious newline from current-command (Rust port regression)

WHen "status current-command" is called outside a function it always returns
"fish". An extra newline crept in, fix that.

Fixes 77aeb6a2a8 (Port execution, 2023-10-08).
Fixes #11503

(cherry picked from commit e26b585ce5)

src/builtins/status.rs

@@ -582,11 +582,10 @@ pub fn status(parser: &Parser, streams: &mut IoStreams, args: &mut [&wstr]) -> O
                 STATUS_CURRENT_CMD => {
                     let command = &parser.libdata().status_vars.command;
                     if !command.is_empty() {
-                        streams.out.append(command);
+                        streams.out.appendln(command);
                     } else {
                         streams.out.appendln(*PROGRAM_NAME.get().unwrap());
                     }
-                    streams.out.append_char('\n');
                 }
                 STATUS_CURRENT_COMMANDLINE => {
                     let commandline = &parser.libdata().status_vars.commandline;

tests/checks/status.fish

@@ -38,6 +38,9 @@ status --job-control=1none
 # Now set it to a valid mode.
 status job-control none
 
+status current-command | sed s/^/^/
+# CHECK: ^fish
+
 # Check status -u outside functions
 status current-function
 #CHECK: Not a function