message: testcase for memory leak in micropython during updating source code, use m_del_obj to delete the replaced module
diff: +import os
  import time
  +import struct
  import wallet
  import eosapi
  import initeos
  +from eosapi import N
  +
  from common import smart_call, producer
  def init(func):
  @@ -25,3 +29,15 @@ def t2():
  assert r
  eosapi.produce_block()
  +@init
  +def test_module_memory_leak(sign=True):
  + _src_dir = os.path.dirname(__file__)
  + actions = []
  + for i in range(10000):
  + code = struct.pack('QBB', N('bugs'), 1, 0)
  + with open(os.path.join(_src_dir, 'bugs.py'), 'rb') as f:
  + code += eosapi.pack_bytes(b'\x00'+f.read() + b'\n1==(%d)'%(i+100,))
  + act = [N('eosio'), N('setcode'), [[N('bugs'), N('active')]], code]
  + cost_time = eosapi.push_transactions2([[act]], sign)
  + if i % 50 == 0:
  + eosapi.produce_block()
  