[INIT] Allow proper throw in compiler (#39)

vta/python/vta/__init__.py

@@ -6,15 +6,17 @@ configure the hardware Environment and  access remote through RPC
 """
 from __future__ import absolute_import as _abs
 
-__version__ = "0.1.0"
+import sys
 
 from .bitstream import get_bitstream_path, download_bitstream
 from .environment import get_env, Environment
 from .rpc_client import reconfig_runtime, program_fpga
 
-try:
+__version__ = "0.1.0"
+
+# do not import nnvm/topi when running vta.exec.rpc_server
+# to maintain minimum dependency on the board
+if sys.argv[0] not in ("-c", "-m"):
     from . import top
     from .build_module import build_config, lower, build
     from . import graph
-except (ImportError, RuntimeError):
-    pass