( By result of discussion in opensuse-factory:
https://lists.opensuse.org/opensuse-factory/2017-07/msg00479.html

Start of discussion:
https://lists.opensuse.org/opensuse-factory/2017-07/msg00414.html )

When using to update openSUSE Tumbleweed this command
zypper dup --no-recommends
some lang packages are going to be removed.

This happens not only for KDE lang packages (at least gstreamer-lang was
noticed as candidate for removing), but it happens frequently for them.

One example was shown in that discussion:

1. We have installed kio (5.35.0), kio-lang (5.35.0), bundle-lang-kde-en (for 
some reason there is no bundle-lang-kde-uk for Ukrainian).
2. Doing update via "zypper dup --no-recommends"

Expected results:
Updating kio to 5.36.0, kio-lang to 5.36.0 and bundle-lang-kde-en to 
13.2-48.2.

Actual results:
Updateing kio to 5.36.0, bundle-lang-kde-en to 13.2-48.2 and removing kio-
lang.

Current example

Installed state:
zypper se -s akonadi-contact
 ...
S  | Name                  | Type    | Version     | Arch   | Repository        
---+-----------------------+---------+-------------+--------+--------------------
i+ | akonadi-contact       | package | 17.04.2-1.2 | x86_64 | (System Packages) 
v  | akonadi-contact       | package | 17.04.3-1.1 | x86_64 |
openSUSE-20170510-0
v  | akonadi-contact       | package | 17.04.2-1.2 | i586   |
openSUSE-20170510-0
 ...
i+ | akonadi-contact-lang  | package | 17.04.2-1.2 | noarch | (System Packages) 
v  | akonadi-contact-lang  | package | 17.04.3-1.1 | noarch |
openSUSE-20170510-0

zypper se -s bundle-lang-kde
 ...
S  | Name               | Type    | Version   | Arch   | Repository         
---+--------------------+---------+-----------+--------+--------------------
 ...
   | bundle-lang-kde-el | package | 13.2-48.3 | noarch | openSUSE-20170510-0
i+ | bundle-lang-kde-en | package | 13.2-48.2 | noarch | (System Packages)  
v  | bundle-lang-kde-en | package | 13.2-48.3 | noarch | openSUSE-20170510-0
   | bundle-lang-kde-es | package | 13.2-48.3 | noarch | openSUSE-20170510-0
 ...

Running zypper dup --no-recommends trying to remove this and some other KDE
packages:

The following 76 packages are going to be REMOVED:
  akonadi-contact-lang akonadi-mime-lang akonadi-notes-lang
 ...
  spectacle-lang systemsettings5-lang

Full logs here: http://paste.opensuse.org/26973391

I'll try not to update for couple of days if some extra info is needed.

In my opinion this is a bug as --no-recommends should prevent installing of new
packages but not updating of already installed ones.