pdflatex breaks on headcolor option in Hyndman template

[AaronGullickson]

The headcolor YAML option in the Hyndman template allows you to specify the color of header text in hexidecimanl format(default is red which I do not care for). This was working fine until recently. However, now I get the following error whenever I reach the pdflatex stage of knitting:

! Missing number, treated as zero.
<to be read again> 
                   \edef 
l.10 \definecolor{headcolor}{HTML}{80}

The error seems to be because my headcolor is "000080" and this is being truncated somewhere as "80" which latex then rightly complains about as not being a proper hexidecimal code. If I put the leading zeroes back in in the produced tex document, it knits fine.

I have tried specifying headcolor without quotations and with a hash in front and neither works.

Repex is provided below. I just started with the basic Hyndman template and added the headcolor field.

---
name: Marie
surname: Curie
position: "Professor"
address: "School of Physics & Chemistry, École Normale Supérieure"
phone: +1 22 3333 4444
www: mariecurie.com
headcolor: "000080"
email: "Marie.Curie@ens.fr"
twitter: mariecurie
github: mariecurie
linkedin: mariecurie
date: "`r format(Sys.time(), '%B %Y')`"
output: vitae::hyndman
---

# Some stuff about me

 * I poisoned myself doing research.
 * I was the first woman to win a Nobel prize
 * I was the first person and only woman to win a Nobel prize in two different sciences.

# Education

* Some University