DEBUG CMDKEYS: provide some guarantee to getKeysFromCommand().
DEBUG CMDKEYS: provide some guarantee to getKeysFromCommand().

getKeysFromCommand() is designed to be called with the command arguments
passing the basic arity checks described in the command table.

DEBUG CMDKEYS must provide the same guarantees for calling
getKeysFromCommand() to be safe.

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