Using label_colour to get edge colour for label colour

[malthesr]

In the man page ?geom_edge_link, under Arguments, it says

label_colour The colour of the edge label. If NA it will use the colour of the edge.

I've been trying to make use of this to make the edge label inherit the colour of its edge, but I can't make it work. Leaving out the label_colour argument gives me black labels, while explicitly setting label_colour = NA removes the edge labels altogether.

MWE to illustrate (ggraph 2.0.2):

library(tidygraph)
#> 
#> Attaching package: 'tidygraph'
#> The following object is masked from 'package:stats':
#> 
#>     filter
library(ggraph)
#> Loading required package: ggplot2

g <- create_ring(10) %>% 
  activate("edges") %>%
  mutate(
    label = letters[1:10],
    colour = rep(c(TRUE, FALSE), 5)
  )

ggraph(g) + 
  geom_edge_link(
    aes(label = label, colour = colour)
  ) +
  geom_node_point()
#> Using `stress` as default layout

ggraph(g) + 
  geom_edge_link(
    aes(label = label, colour = colour),
    label_colour = NA # Makes the labels disappear
  ) +
  geom_node_point()
#> Using `stress` as default layout

^{Created on 2020-03-21 by the reprex package (v0.2.1)}

Am I misunderstanding the docs here? I would've thought that either of these would've made the edge labels take the colours of their associated edge. As far as I can tell, the same thing happens label_alpha.

Thank you for a great package.