Ignore serial number "blank" from NUT (#63066)

homeassistant/components/nut/__init__.py

@@ -31,6 +31,8 @@ from .const import (
     PYNUT_UNIQUE_ID,
 )
 
+NUT_FAKE_SERIAL = ["unknown", "blank"]
+
 _LOGGER = logging.getLogger(__name__)
 
 
@@ -145,7 +147,9 @@ def _firmware_from_status(status):
 def _serial_from_status(status):
     """Find the best serialvalue from the status."""
     serial = status.get("device.serial") or status.get("ups.serial")
-    if serial and (serial.lower() == "unknown" or serial.count("0") == len(serial)):
+    if serial and (
+        serial.lower() in NUT_FAKE_SERIAL or serial.count("0") == len(serial)
+    ):
         return None
     return serial