bugfix for Expression.Disjunction: was a conjunction before #380

Job	Run time
Test and Deploy on latest (Debug)	16m 27s
Test on stable (Debug)	10m 10s
Indepth Tests (Debug, all libraries)	18m 19s
Test and Deploy on latest (Release)	16m 50s
Test on stable (Release)	10m 4s
Indepth Tests (Debug, no libraries)	13m 36s
Indepth Tests (Release, all libraries)	15m 50s
Indepth Tests (Release, no libraries)	13m 31s
Email notification	5s
	1h 54m 52s

Provide feedback