test_broken_pipe_no_error intermittent failure

---- test_tr::test_broken_pipe_no_error stdout ----
bin: "/Users/runner/work/coreutils/coreutils/target/x86_64-apple-darwin/debug/coreutils"
run: /Users/runner/work/coreutils/coreutils/target/x86_64-apple-darwin/debug/coreutils tr e a

thread 'test_tr::test_broken_pipe_no_error' panicked at tests/by-util/test_tr.rs:1597:10:
assertion failed: !self.succeeded()
stack backtrace:
   0: __rustc::rust_begin_unwind
             at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/std/src/panicking.rs:697:5
   1: core::panicking::panic_fmt
             at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/panicking.rs:75:14
   2: core::panicking::panic
             at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/panicking.rs:145:5
   3: uutests::util::CmdResult::fails_silently
             at ./tests/uutests/src/lib/util.rs:707:9
   4: tests::test_tr::test_broken_pipe_no_error
             at ./tests/by-util/test_tr.rs:1593:5
   5: tests::test_tr::test_broken_pipe_no_error::{{closure}}
             at ./tests/by-util/test_tr.rs:1592:31
   6: core::ops::function::FnOnce::call_once
             at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/ops/function.rs:250:5
   7: core::ops::function::FnOnce::call_once
             at /rustc/6b00bc3880198600130e1cf62b8f8a93494488cc/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Start with tests/by-util/test_tr.rs around test_broken_pipe_no_error at line 1597, then inspect tests/uutests/src/lib/util.rs around CmdResult::fails_silently. Run the focused test repeatedly to reproduce the intermittent failure and trace why the command is reported as succeeded. Done means the test reliably validates the broken-pipe behavior without intermittent failure.