fix ipc/user:ipc_test intermittent failure

MODULE.bazel

diff --git a/MODULE.bazel b/MODULE.bazel
index 896d71e..677e127 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -29,6 +29,8 @@
         # Allow integration_tests to build for armv7-m / armv7e-m so the
         # AST10x0 unittest_runner can use it.
         "//third_party/pigweed:integration_tests_armv7m.patch",
+        # Fix lost-wakeup race in ipc/user test USER signal round-trip.
+        "//third_party/pigweed:ipc_user_signal_race.patch",
     ],
     remote = "https://pigweed.googlesource.com/pigweed/pigweed",
 )

third_party/pigweed/ipc_user_signal_race.patch

diff --git a/third_party/pigweed/ipc_user_signal_race.patch b/third_party/pigweed/ipc_user_signal_race.patch
new file mode 100644
index 0000000..57b8859
--- /dev/null
+++ b/third_party/pigweed/ipc_user_signal_race.patch
@@ -0,0 +1,14 @@
+--- a/pw_kernel/tests/ipc/user/handler.rs
++++ b/pw_kernel/tests/ipc/user/handler.rs
+@@ -31,8 +31,9 @@
+         // USER signal means the initiator is pinging us; echo it back and lower it
+         // (level-triggered: the sender owns both raise and lower).
+         if wait_return.pending_signals.contains(Signals::USER) {
+             syscall::object_set_peer_user_signal(handle::IPC, true).map_err(|_| Error::Internal)?;
+-            syscall::object_set_peer_user_signal(handle::IPC, false)
+-                .map_err(|_| Error::Internal)?;
++            // Do not lower: initiator may not have reached object_wait yet.
++            // syscall::object_set_peer_user_signal(handle::IPC, false)
++            //     .map_err(|_| Error::Internal)?;
+             return Ok(());
+         }