Log host info with uri

[John Lauro]

Is there an easy way to have haproxy log the host with the uri instead of
just the relative uri?  I have some 503 errors, and they are going to
virtual hosts on the backend and I am having some trouble tracking them
down.  and the uri isn't specific enough as it is common among multiple
hosts.  I'm sure this can be done, just having trouble figuring it out at
the moment.