Steps to reproduce the issue

$ spack env create my-jupyter
$ spack env activate my-jupyter
$ spack add py-jupyter
$ spack add py-ipython
$ spack add py-ipykernel
$ spack add py-notebook
$ spack install

Error Message

If I try to start jupyter notebook now and open a Python3 Notebook I get no working Python3 kernel

Kernel started: af71e14f-24f7-40a4-92a8-48e79f5d621c, name: python3
/home/axel/src/spack/opt/spack/linux-ubuntu18.04-skylake/gcc-8.4.0/python-3.8.6-wuh5zypqqvf3fba4ootslwky3plqqsqw/bin/python3.8: No module named ipykernel_launcher

[I 00:55:29.178 NotebookApp] KernelRestarter: restarting kernel (1/5), new random ports
/home/axel/src/spack/opt/spack/linux-ubuntu18.04-skylake/gcc-8.4.0/python-3.8.6-wuh5zypqqvf3fba4ootslwky3plqqsqw/bin/python3.8: No module named ipykernel_launcher

# ...

Information on your system

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.5 LTS
Release:	18.04
Codename:	bionic

spack debug report:

• Spack: 0.15.4-1470-99ef3d11c1
• Python: 3.8.6
• Platform: linux-ubuntu18.04-skylake

Additional information

• I have run spack debug report and reported the version of Spack/Python/Platform
• I have searched the issues of this repo and believe this is not a duplicate
• I have run the failing commands in debug mode and reported the output