luaRedisGenericCommand(): log error at WARNING level when re-entered.
luaRedisGenericCommand(): log error at WARNING level when re-entered.

Rationale is that when re-entering, it is likely due to Lua debugging
hooks. Returning an error will be ignored in most cases, going totally
unnoticed. With the log at least we leave a trace.

Related to issue #2302.

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