This is most likely the same bug in dpkg already reported as #911620 and
#911822, relevant part of the log:
dpkg: cycle found while processing triggers:
chain of packages whose triggers are or may be responsible:
gconf2 -> gosa
packages' pending triggers which are or may be unresolvable:
dpkg: error processing package systemd (--configure):
triggers looping, abandoned
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed