Slpkg testing log:

The majority of trials have been made in an environment Slackware x86_64 and x86 stable version 
14.1.
Is logical tests are always to be latest versions of the distribution.
Slpkg are supported version 'current' but it is minimal tests have been done on this release.


TEST:

Distribution : Slackware Linux
Release : 14.1
Version : stable
Arch : x86, x86_64

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19-12-2014
Slackware Arch: x86_64, Version: 14.1 'stable'

Test to upgrade Slackware Linux Distribution.
Successful upgrade fresh full installation with command 'slpkg -c slack --upgrade'
Total 54 packages upgraded and kernel, after auto-install 'lilo' reinstall successfully so.

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20-12-2014
Slackware Arch: x86 Version 14.1 'current'

Test to upgrade Slackware Linux Distribution.
Successful upgrade fresh full installation with command 'slpkg -c slack --upgrade'
Total 66 packages upgraded and kernel, after auto-install 'lilo' reinstall successfully so.

--------------------------------
11-2-2015
Slackware Arch: x86 Version 14.1 'current'

Test to upgrade fresh installation Slackware Linux Distribution.
Successful upgrade fresh full installation with command 'slpkg -c slack --upgrade'
Total 78 packages upgraded and kernel, after auto-install 'lilo' reinstall successfully so.
https://asciinema.org/a/16289

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24-2-2015
Slackware Arch: x86_64 Version 14.1 'stable'

Test to upgrade fresh installation Slackware Linux Distribution.
Successful upgrade fresh full installation with command 'slpkg -c slack --upgrade'
Total 62 packages upgraded and kernel, after auto-install 'lilo' reinstall successfully so.
https://asciinema.org/a/16889

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04-02-2016
Slackware Arch: x86 Version 14.2 'current'

Test to upgrade Slackware Linux Distribution.
Successful upgrade with command 'slpkg -c slack --upgrade skip="slack:kde-l10n*,slack:calligra-l10n*"
Total 42 packages upgraded with kernel and 2 new packages installed.
http://pastebin.com/3gbc77Wj