pycapnp bug

bad.py

import capnp  # noqa
from bug_capnp import Msg

with open('test.bin', 'rb') as f:
    for m in Msg.read_multiple(f):
        pass

bug.capnp

@0x9bb8c5815bdb9a65;
struct Msg {
  data @0 :List(UInt8);
}

gen.py

import capnp  # noqa
from bug_capnp import Msg


with open('test.bin', 'wb') as f:
    msg1 = Msg.new_message()
    msg1.data = [0x41] * 8192
    msg1.write(f)
    msg2 = Msg.new_message()
    msg2.write(f)

good.py

import capnp  # noqa
from bug_capnp import Msg

with open('test.bin', 'rb') as f:
    for m in Msg.read_multiple(f):
        del m

test.bin






                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                