Multiple fixes for EVAL (issue #872).
Multiple fixes for EVAL (issue #872).

1) The event handler was no restored after a timeout condition if the
   command was eventually executed with success.
2) The command was not converted to EVAL in case of errors in the middle
   of the execution.
3) Terrible duplication of code without any apparent reason.

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis