I'm trying to build python-matplotlib from the Danny branch of
meta-openembedded/meta-oe/recipes-devtools/python. I need to add a
setup.cfg file to tweak the build, but I don't know how to get it into the
right place.

I put the setup.cfg into a python-matplotlib subdirectory in my recipes
directory, and added a python-matplotlib_1.1.0.bbappend file which
contains the following lines:

FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
PRINC := "${@int(PRINC) + 2}"
SRC_URI += "file://setup.cfg"

The file is being copied into
.../work/armv7a-vfp-neon-poky-linux-gnueabi/python-matplotlib-1.1.0-r3
rather than
.../work/armv7a-vfp-neon-poky-linux-gnueabi/python-matplotlib-1.1.0-r3/mat
plotlib-1.1.0 where it needs to be. How do I push it down a level?