R dendextend set "leaves_col" converts leaves pch to character

Question

I am creating a dendrogram using dendextend and wish to set leaves as colored symbols.

require(ggplot2)
require(dendextend)

sessionInfo()
R version 3.1.3 (2015-03-09)
Platform: x86_64-apple-darwin10.8.0 (64-bit)
Running under: OS X 10.10.5 (Yosemite)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] dendextend_0.18.3 ggplot2_1.0.1    

Make a simple dendrogram

data(USArrests)

dend = USArrests[1:5,] %>% 
    scale %>%
    dist %>% 
    hclust %>% 
    as.dendrogram

Setting leaves_pch works fine

dend1 = dend %>%
    set("leaves_pch", 19)

get_leaves_attr(dend1, "nodePar", simplify=T)
  pch pch pch pch pch 
   19  19  19  19  19 

Plots as expected

plot(dend1)

But when I add colors the pch values convert to character

dend2 = dend %>%
    set("leaves_pch", 19) %>%
    set("leaves_col", "blue")


get_leaves_attr(dend2, "nodePar", simplify=T)
   pch    col    pch    col    pch    col    pch    col    pch    col 
  "19" "blue"   "19" "blue"   "19" "blue"   "19" "blue"   "19" "blue" 

Causing problems with plotting

plot(dend2)

Is there a workaround? I'm sure I'm missing something simple...