AD fix for PDBijector #498

Job	Run time
test (1.6, ubuntu-latest, x64, ForwardDiff)	5m 25s
test (1.6, ubuntu-latest, x64, Tracker)	5m 5s
test (1.6, ubuntu-latest, x64, ReverseDiff)	6m 10s
test (1.6, ubuntu-latest, x64, Zygote)	6m 32s
test (1.6, macOS-latest, x64, ForwardDiff)	6m 14s
test (1.6, macOS-latest, x64, Tracker)	5m 37s
test (1.6, macOS-latest, x64, ReverseDiff)	7m 32s
test (1.6, macOS-latest, x64, Zygote)	7m 38s
test (1, ubuntu-latest, x64, ForwardDiff)	6m 37s
test (1, ubuntu-latest, x64, Tracker)	5m 27s
test (1, ubuntu-latest, x64, ReverseDiff)	6m 0s
test (1, ubuntu-latest, x64, Zygote)	7m 12s
test (1, macOS-latest, x64, ForwardDiff)	7m 9s
test (1, macOS-latest, x64, Tracker)	6m 38s
test (1, macOS-latest, x64, ReverseDiff)	7m 28s
test (1, macOS-latest, x64, Zygote)	8m 32s
	1h 45m 16s

Provide feedback