fix(yes): restore SIGPIPE to default handler

Fixes broken pipe handling by unconditionally restoring SIGPIPE to SIG_DFL
at program startup, following the established pattern used in cat, tr, and
tail utilities.

This ensures the process properly terminates with exit code 141 when writing
to closed pipes, rather than ignoring SIGPIPE as Rust does by default.

Related to issue #7252 and PR #9560.

Author: naoNao89

src/uu/stty/src/stty.rs

@@ -997,7 +997,7 @@ fn apply_char_mapping(termios: &mut Termios, mapping: &(S, u8)) {
 ///
 /// The state array contains:
 /// - `state[0]`: input flags
-/// - `state[1]`: output flags  
+/// - `state[1]`: output flags
 /// - `state[2]`: control flags
 /// - `state[3]`: local flags
 /// - `state[4..]`: control characters (optional)

tests/by-util/test_ls.rs

@@ -6498,7 +6498,7 @@ fn test_f_overrides_sort_flags() {
 
     // Create files with different sizes for predictable sort order
     at.write("small.txt", "a"); // 1 byte
-    at.write("medium.txt", "bb"); // 2 bytes  
+    at.write("medium.txt", "bb"); // 2 bytes
     at.write("large.txt", "ccc"); // 3 bytes
 
     // Get baseline outputs (include -a to match -f behavior which shows all files)

tests/by-util/test_yes.rs

@@ -126,7 +126,7 @@ fn test_normal_pipe_sigpipe() {
 
     // Run `yes | head -n 1` via shell with pipefail to capture yes's exit code
     // In this scenario, SIGPIPE is not trapped, so yes should be killed by the signal
-    let output = Command::new("sh")
+    let output = Command::new("bash")
         .arg("-c")
         .arg(format!(
             "set -o pipefail; {} yes | head -n 1 > /dev/null",
@@ -142,9 +142,6 @@ fn test_normal_pipe_sigpipe() {
     // Exit code should be 141 (128 + 13) on most Unix systems
     // OR the process was terminated by signal (status.code() returns None)
     if let Some(code) = exit_code {
-        println!("Exit code: {code}");
-        println!("Stderr: {}", String::from_utf8_lossy(&output.stderr));
-
         assert_eq!(
             code, 141,
             "yes should exit with code 141 (killed by SIGPIPE), but got {code}"
@@ -153,7 +150,6 @@ fn test_normal_pipe_sigpipe() {
         // Process was terminated by signal (which is also acceptable)
         use std::os::unix::process::ExitStatusExt;
         let signal = output.status.signal().unwrap();
-        println!("Terminated by signal: {signal}");
         // Signal 13 is SIGPIPE
         assert_eq!(signal, 13, "yes should be killed by SIGPIPE (13)");
     }