ImportError: cannot import name 'default_gui_banner'

env:
mac: 10.13.6
python: Python 3.6.0 (v3.6.0:41df79263a11, Dec 22 2016, 17:23:13)
all the pip, jupyter, notebook are latest.

```
WARNING:root:kernel ae65b357-ee9b-418e-9e20-951e8f7e5877 restarted
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/runpy.py", line 193, in _run_module_as_main
"__main__", mod_spec)
File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/Users/py3env/lib/python3.6/site-packages/ipykernel/__main__.py", line 2, in
from ipykernel import kernelapp as app
File "/Users/py3env/lib/python3.6/site-packages/ipykernel/kernelapp.py", line 37, in
from .ipkernel import IPythonKernel
File "/Users/py3env/lib/python3.6/site-packages/ipykernel/ipkernel.py", line 15, in
from .zmqshell import ZMQInteractiveShell
File "/User/py3env/lib/python3.6/site-packages/ipykernel/zmqshell.py", line 35, in
from IPython.core.usage import default_gui_banner
ImportError: cannot import name 'default_gui_banner'
[W 17:25:02.663 NotebookApp] KernelRestarter: restart failed
[W 17:25:02.664 NotebookApp] Kernel ae65b357-ee9b-418e-9e20-951e8f7e5877 died, removing from map.
ERROR:root:kernel ae65b357-ee9b-418e-9e20-951e8f7e5877 restarted failed!
[W 17:25:02.685 NotebookApp] 410 DELETE /api/sessions/285bed08-c1f6-47e2-980d-ada309f17398 (::1): Kernel deleted before session
[W 17:25:02.686 NotebookApp] Kernel deleted before session
[W 17:25:02.687 NotebookApp] 410 DELETE /api/sessions/285bed08-c1f6-47e2-980d-ada309f17398 (::1) 6.11ms referer=http://localhost:8888/notebooks/Untitled.ipynb
```

Start by reproducing kernel startup from the reported Python 3.6/macOS environment and inspect the import path through ipykernel/__main__.py, kernelapp.py, ipkernel.py, and zmqshell.py. Done means the notebook kernel starts without the default_gui_banner ImportError and the reported restart failure is gone.

Written by the indexing model from the issue text.