Panic on too many/large transactions

[tomtau]

I'm running on Tendermint 0.25 with this patched version: 90dad48

With too many/large transactions, rust-tsp will panic:

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: Custom { kind: WriteZero, error: StringError("failed to write whole buffer") }', libcore/result.rs:1009:5

stack backtrace:

   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:211
   3: std::panicking::default_hook
             at libstd/panicking.rs:227
   4: <std::panicking::begin_panic::PanicPayload<A> as core::panic::BoxMeUp>::get
             at libstd/panicking.rs:477
   5: std::panicking::continue_panic_fmt
             at libstd/panicking.rs:391
   6: std::panicking::try::do_call
             at libstd/panicking.rs:326
   7: core::ptr::drop_in_place
             at libcore/panicking.rs:77
   8: core::alloc::Layout::repeat
             at libcore/macros.rs:26
   9: <bytes::bytes::BytesMut as core::convert::AsRef<[u8]>>::as_ref
             at libcore/result.rs:808
  10: <protobuf::cached_size::CachedSize as core::default::Default>::default
             at ~/.cargo/git/checkouts/rust-tsp-6c1140b7f202a3ea/90dad48/src/server.rs:150
  11: abci::server::respond
             at ~/.cargo/git/checkouts/rust-tsp-6c1140b7f202a3ea/90dad48/src/server.rs:118
  12: abci::server::handle_stream
             at ~/.cargo/git/checkouts/rust-tsp-6c1140b7f202a3ea/90dad48/src/server.rs:62
  13: abci::server::serve::{{closure}}
             at ~/.cargo/git/checkouts/rust-tsp-6c1140b7f202a3ea/90dad48/src/server.rs:34

[tomtau]

fix in #21