fix socket.error raises

Fixes aio-libs-abandoned#1121

aioredis/connection.py

@@ -52,6 +52,16 @@
     ssl.SSLError: 2,
 }
 
+# In Python 2.7 a socket.error is raised for a nonblocking read.
+# The _compat module aliases BlockingIOError to socket.error to be
+# Python 2/3 compatible.
+# However this means that all socket.error exceptions need to be handled
+# properly within these exception handlers.
+# We need to make sure socket.error is included in these handlers and
+# provide a dummy error number that will never match a real exception.
+if socket.error not in NONBLOCKING_EXCEPTION_ERROR_NUMBERS:
+    NONBLOCKING_EXCEPTION_ERROR_NUMBERS[socket.error] = -999999
+
 NONBLOCKING_EXCEPTIONS = tuple(NONBLOCKING_EXCEPTION_ERROR_NUMBERS.keys())
 
 try: