Fix IO worker tolerance of errors

If an _io_apply encounters an exception, the io worker entirely would fall apart.  Encompass the key entry
points in try clauses to allow the thread to keep working and the dependent IPMI object to have their
waiter acknowledged.  It's still considered a grave bug for this to ever occur, but at least
the application would carry on.

Change-Id: I61b0797025b25c6d9d3e86a5110603a6fc2d67fb

pyghmi/ipmi/private/session.py

@@ -27,6 +27,7 @@ import select
 import socket
 import struct
 import threading
+import traceback
 
 from Crypto.Cipher import AES
 
@@ -109,10 +110,16 @@ def _ioworker():
             workitem = ioqueue.popleft()
             # structure is function, args, list to append to ,event to set
             if isinstance(workitem[1], tuple):  # positional arguments
-                workitem[2].append(workitem[0](*workitem[1]))
+                try:
+                    workitem[2].append(workitem[0](*workitem[1]))
+                except Exception:
+                    traceback.print_exc()
                 workitem[3].set()
             elif isinstance(workitem[1], dict):
-                workitem[2].append(workitem[0](**workitem[1]))
+                try:
+                    workitem[2].append(workitem[0](**workitem[1]))
+                except Exception:
+                    traceback.print_exc()
                 workitem[3].set()
             elif workitem[0] == 'wait':
                 if len(rdylist) > 0:
@@ -139,7 +146,10 @@ def _io_apply(function, args):
 def _io_sendto(mysocket, packet, sockaddr):
     #Want sendto to act reasonably sane..
     mysocket.setblocking(1)
-    mysocket.sendto(packet, sockaddr)
+    try:
+        mysocket.sendto(packet, sockaddr)
+    except Exception:
+        pass
 
 
 def _io_recvfrom(mysocket, size):