Regression: some (nested) `select` expressions do not work

With the current master this does not work anymore (while it used to with previous versions):

muRecoilJets = op.select(cleanedJets, partial((lambda l,j : op.deltaR(l.p4, j.p4) > 0.7), muons[0]))

(with both cleanedJets and muons selected/cleaned object collections)

I am debugging, but maybe wait a bit with updating in case you frequently use this kind of construction.