After ac27d1c93b if a read executor has just enough targets to
achieve request's CL and a connection to one of them will be dropped
during execution ReadFailed error will be returned immediately and
client will not have a chance to issue speculative read (retry). The
patch changes the code to not return ReadFailed error immediately, but
wait for timeout instead and give a client chance to issue speculative
read in case read executor does not have additional targets to send
speculative reads to by itself.
Fixes#3699.
Message-Id: <20180819131646.GK2326@scylladb.com>
7277ee2939