fix(mosaic): retry the Invariant R pi version probe under CI load (#1441)

packages/mosaic/src/lease-broker/invariant_r_unittest.py

@@ -75,7 +75,7 @@ def run_pi_registry_command(
     runner=subprocess.run,
     sleeper=time.sleep,
 ) -> subprocess.CompletedProcess[str]:
-    """Run the registry probe with bounded retries for concurrent-Pi stalls."""
+    """Run a Pi probe command with bounded retries for concurrent-Pi stalls."""
 
     for attempt in range(1, PI_PROBE_ATTEMPTS + 1):
         try:
@@ -106,13 +106,7 @@ def probe_pi_registry() -> list[dict[str, object]]:
     if pi is None:
         raise AssertionError("installed Pi runtime is required for Invariant R")
 
-    version = subprocess.run(
-        [pi, "--version"],
-        check=False,
-        capture_output=True,
-        text=True,
-        timeout=10,
-    )
+    version = run_pi_registry_command([pi, "--version"], dict(os.environ))
     if version.returncode != 0:
         raise AssertionError(f"Pi version probe failed: {version.stderr.strip()}")
     if version.stdout.strip() != PI_VERSION: