In standalone mode, when a `-REDIRECT` error occurs, special handling is
required if the client is in the `MULTI` context.
We have adopted the same handling method as the cluster mode:
1. If a command in the transaction encounters a `REDIRECT` at the time
of queuing, the execution of `EXEC` will return an `EXECABORT` error (we
expect the client to redirect and discard the transaction upon receiving
a `REDIRECT`). That is:
```
MULTI ==> +OK
SET x y ==> -REDIRECT
EXEC ==> -EXECABORT
```
2. If all commands are successfully queued (i.e., `QUEUED` results are
received) but a redirect is detected during `EXEC` execution (such as a
primary-replica switch), a `REDIRECT` is returned to instruct the client
to perform a redirect. That is:
```
MULTI ==> +OK
SET x y ==> +QUEUED
failover
EXEC ==> -REDIRECT
```
---------
Signed-off-by: zhaozhao.zz <zhaozhao.zz@alibaba-inc.com>
743f5ac2ae