Client requires a call to `get_read_version()` before being able to read

If the read version for the very first transaction through a client is manually specified via `set_read_version()`, the client will immediately return with transaction too old. If you create a dummy transaction and call `get_read_version()` on that transaction, all future transactions with a manually specified `set_read_version()` will work as expected.

From a casual inspection, https://github.com/apple/foundationdb/blob/master/fdbclient/DatabaseContext.h#L249 appears to be the offending code.