unnest chokes on syntactically invalid variable names

[lukeanker]

unnest refuses to process data frames with syntactically invalid column names (e.g. containing spaces or beginning with numbers):

library(dplyr)
library(tidyr)
dat <- data.frame("foo bar" = I(list(1:2, 3)), check.names = F)
unnest(dat)
# Error in parse(text = x) : <text>:1:5: unexpected symbol
#1: foo bar
#         ^

unnest_(dat, names(dat))
# Error in parse(text = x) : <text>:1:5: unexpected symbol
#1: foo bar
#         ^

dat %>% rename(foobar=`foo bar`) %>% unnest
# Source: local data frame [3 x 1]
# 
#   foobar
#    (dbl)
#1      1
#2      2
#3      3

I don't know if it's a bug or if I'm using the function wrongly, but I think it worked in previous versions of tidyr. I'm packageVersion("tidyr") ‘0.4.1’ and packageVersion("dplyr") ‘0.4.3’

[hadley]

Simpler reprex:

library(tibble)
library(tidyr)

data_frame("foo bar" = list(1:2, 3)) %>% unnest()