4.0.1 update on Ubuntu changes?

I noticed an update to 4.0.1 on Ubuntu today. Does anybody know what has been fixed/changed?

See the announcement on KiCad’s blog:

In short: safe to update, the devs were very cautious about regressions.

Ah, I might have missed the point of your question.
Maybe you’re wondering why Ubuntu suggests updating the package although you were already using 4.0.1.

It seems that the “PPA for KiCad 4.0” is often rebuilt (daily?), see:

There probably hasn’t been any meaningful change since the day 4.0.1 was released but Ubuntu doesn’t know that, because the changelog contains the build date. Here is a list of the latest changes to the binary package:
https://launchpadlibrarian.net/236923526/kicad-doc_4.0.1-0.201602041347+866~12~ubuntu14.04.1_4.0.1-0.201602080146+866~12~ubuntu14.04.1.diff.gz

I will tell the maintainer, hopefully we can fix this.

To clarify, I am using the 4.0 stable PPA, not the nightly testing build. I suspect some bug fixes have been merged.
When 4.0.1 was released, it was clear that this was to fix the library path error, so I was able to stop correcting the problem manually.
Sometimes bug fixes cause new unexpected side effects, so it helps to know what has happened

Yes, I was talking about the 4.0 stable PPA.

My understanding was incorrect though. After discussion with the maintainer (@jsreynaud), it appears that the PPA was changing for every commit in the 4.0 branch.

@jsreynaud just changed the PPA behaviour to stick with 4.0.1 until the next release/tag.

4.0.1-4 20160212 update rolled in yesterday and today on my machines.

I guess the changes are very minor…

Now updated to 4.0.2-4+6225~38~ubuntu14.04.1