weird behaviour of slackpkg compared to slapt-get

While I was trying the package slapt-get and tested it, I was surprised to see that:
- slapt-get showed me python-docutils to upgrade from 0.16 to 0.17 version
- I looked at /var/log/packages to see if python-docutils was really 0.16, and it was
- "slackpkg upgrade-all" didn't show me python-docutils to upgrade

I have no package of that sort in blacklist of greylist of slackpkg.
I have the same mirror for slackpkg and SOURCE for slapt-get.

Can someone make the same test as me?
Is it a corner case?