Crash in eval/4

[bjosv]

The eval/4 consists of two steps

• first an EVALSHA that tries to run an already loaded script
• if the Redis node dont have the script it will be loaded using SCRIPT LOAD

if the Redis node is stopped or crashes right before the SCRIPT LOAD the socket gets closed
and the query will return {error, no_connection} which is unmatched.

A testcase to trigger the issue, using a fake Redis cluster, can be found here:
Nordix/pull/35