Do not load 'netutils' w/o 'netaddr' python library

Change-Id: I6fb5a46271933fae5cc282877597ec351eed7b3d
Related: PROD-27273
(cherry picked from commit def2816c0a34d5379c7e77ef7f9d446295452242)
diff --git a/_modules/netutils.py b/_modules/netutils.py
index 6cc8e83..2be6079 100644
--- a/_modules/netutils.py
+++ b/_modules/netutils.py
@@ -1,10 +1,17 @@
 from itertools import chain
-from netaddr import iter_iprange, IPAddress, IPNetwork
+
+try:
+    from netaddr import iter_iprange, IPAddress, IPNetwork
+    HAS_NETADDR = True
+except ImportError:
+    HAS_NETADDR = False
 
 __virtualname__ = 'netutils'
 
 
 def __virtual__():
+    if not HAS_NETADDR:
+        return False, "'netaddr' python library is unavailable"
     return __virtualname__