tcp debugging: allow switching on TCP debug by env var

Print monitoring info about TCP sockets when the env var
OSMOPY_DEBUG_TCP_SOCKETS is present and not "0".

Makes it easy to enable it on jenkins without blowing up output of normal runs
"at home".

Change-Id: I46212d07a2c1be05672a37766457e6c98b68f90d

osmopy/obscvty.py

@@ -19,6 +19,7 @@
 import re
 import socket
 import sys, subprocess
+import os
 
 """VTYInteract: interact with an osmocom vty
 
@@ -26,7 +27,7 @@ Specify a VTY to connect to, and run commands on it.
 Connections will be reestablished as necessary.
 Methods: __init__, command, enabled_command, verify, w_verify"""
 
-debug_tcp_sockets = False
+debug_tcp_sockets = (os.getenv('OSMOPY_DEBUG_TCP_SOCKETS', '0') != '0')
 
 def cmd(what):
     print '\n> %s' % what