type.convert and doubles
Strictly speaking, I don't think this is true. If it were, it would not have been necessary to make the change so that it does now fallback to using character/factor. It may, however, have always been the intent. I don't really think a warning is necessary, but there are some surprises:
str(type.convert(format(1/3, digits=17))) # R-3.0.3
num 0.333
str(type.convert(format(1/3, digits=17))) # R-3.1.0
Factor w/ 1 level "0.33333333333333331": 1
It is bizarre that it makes a factor rather than a string. 0.333333333333 is pretty obviously not a categorical value. Hadley