Description of problem:
I am (and have been for many years) on a de_DE.UTF-8 system locale.
After upgrading to Fedora 28 via dnf system-upgrade gnome-terminal-server.service failed to start and shells in the "text mode" virtual consoles emitted warnings about locales.

Running 
dnf install glibc-langpack-de
resolved the issue.

Version-Release number of selected component (if applicable):
Not sure. It was the latest FC-27 version of dnf.


How reproducible:
Maybe install FC-27 from scratch, set a system locale LANG=de_DE.UTF-8
and upgrade to FC-28 using
dnf upgrade --refresh
dnf install dnf-plugin-system-upgrade
dnf system-upgrade download --refresh --releasever=25
dnf system-upgrade reboot



Steps to Reproduce:
1.
2.
3.

Actual results:
Shells in virtual consoles emitted warnings about locales (setlocale: LC_TIME: Cannot change default settings) and Gnome Terminal under Wayland fails to start.

Expected results:
Working Gnome Terminal

Additional info:
Running 
dnf install glibc-langpack-de
resolved the issue.