libcurl did a superfluous 1000ms wait when doing SFTP downloads!

  We read data with libssh2 while doing the "DO" operation for SFTP and then
  when we were about to start getting data for the actual file part, the
  "TRANSFER" part, we waited for socket action (in 1000ms) before doing a
  libssh2-read. But in this case libssh2 had already read and buffered the
  data so we ended up always just waiting 1000ms before we get working on the
  data!