Blocking does not work if blocking.cv = TRUE is not set in makeResampleDesc()

[pat-s]

library(mlr)
blocks = factor(sample(letters[1:4], nrow(iris), replace = TRUE))
task = makeClassifTask("iris", iris, target = "Species", blocking = blocks)
learner = makeLearner("classif.rpart")
rdesc = makeResampleDesc("Subsample", iters = 3)
# no blocking!
resample(learner, task, rdesc)

Even though this is documented in the articles, it can be easily forgotten by the user, leading to unnoticed undesired behavior.

A warning could be issued to notify users.