Add a check for a 'maint' file and return immediately if it exists, in

case things are under maintenance.

sensors/nfstrace/nfstrace.proxy

@@ -5,6 +5,7 @@ import sys
 import time
 import socket
 import getopt
+import os, os.path
 
 import MySQLdb
 
@@ -19,6 +20,11 @@ except IOError:
     sys.exit(1)
     pass
 
+if os.path.exists("/var/nfstrace/maint"):
+    # sys.stderr.write("not available\n")
+    sys.exit(0)
+    pass
+
 VERBOSITY = 1
 
 GC_TABLES = [