Quoting myself:
"""
para ipython-owner
---
Hi,
Is there some work on updating to ipython5?
I did some initial work just to get a feeling on how it should be
done, but did not yet check packages that (build?) requires ipython.
I need it for sagemath 7.4 on rawhide. Previously I was doing
some patches to make it work with ipython3, but the patch no
longer work (worked last for sagemath 7.3), so, my current WIP
sagemath 7.4 package is installing a bundled ipython 5.0.0.
Thanks,
Paulo
"""
I just opened this bug report as an "excuse" for possible
issues for importing ipykernel, that at first only sagemath
will use, and newer sagemath should (temporarily) bundle
ipython 5.
The quoted email above was sent 16 November.