TST: additional network failure detection

Author: jreback

pandas/util/testing.py

@@ -1295,6 +1295,7 @@ def dec(f):
 # or this e.errno/e.reason.errno
 _network_errno_vals = (
     101, # Network is unreachable
+    111, # Connection refused
     110, # Connection timed out
     104, # Connection reset Error
     54,  # Connection reset by peer