More variadic MIGRATE fixes.
More variadic MIGRATE fixes.

Another leak was fixed in the case of syntax error by restructuring the
allocation strategy for the two dynamic vectors.

We also make sure to always close the cached socket on I/O errors so that
all the I/O errors are handled the same, even if we had a previously
queued error of a different kind from the destination server.

Thanks to Kevin McGehee. Related to issue #3016.

pedigree/redis,pedigree/redis,pedigree/redis,xuguruogu/redis,xuguruogu/redis,4396/redis,4396/redis,janekmi/redis,xuguruogu/redis,xuguruogu/redis,pedigree/redis,janekmi/redis,4396/redis,janekmi/redis,janekmi/redis,4396/redis