Ok clone as OpenOCD repo as normal, eg.
git clone http://git.code.sf.net/p/openocd/code openocd
then to add my change
git fetch http://openocd.zylin.com/openocd refs/changes/10/1010/1 && git checkout FETCH_HEAD
to build you then do
only required once on a new clone
./bootstrap
configure build
./configure --enable-maintainer-mode --disable-werror --enable-stlink
and build
make
Cheers
Spen