autobuilder.sh
--- /tmp/test/gitbuilder/autobuilder.sh 2015-08-21 13:53:31.971931227 +0800
+++ autobuilder.sh      2015-07-02 10:59:09.588364316 +0800
@@ -54,6 +54,12 @@
                trap "echo 'Killing (SIGINT)';  kill -TERM -$XPID; exit 1" SIGINT
                trap "echo 'Killing (SIGTERM)'; kill -TERM -$XPID; exit 1" SIGTERM
                wait; wait
+               mkdir -p /ceph_repos/ceph-deb-trusty-x86_64-basic/ref/${branch#*/}
+               cp -r --preserve=links /ceph_tmp/release/Ubuntu/{conf,db,dists,pool,trusty,version} /ceph_repos/ceph-deb-trusty-x86_64-basic/ref/${branch#*/}
+               echo $ref > /ceph_repos/ceph-deb-trusty-x86_64-basic/ref/${branch#*/}/sha1
+
+               ln -s /ceph_repos/ceph-deb-trusty-x86_64-basic/ref/${branch#*/} /ceph_repos/ceph-deb-trusty-x86_64-basic/sha1/$ref
+               rm -rf /ceph_tmp/release/*
        done

        sleep 5

branches-local
you can use the easy way to assign to branch which you want it.
example:
branches-local.bak
#!/bin/sh
echo 'origin/dillaman_librbd_cache_2'

branches.sh
you need change branches script
example:
#!/bin/bash
DIR=$(dirname $0)
cd "$DIR/build"

if [ -x ../branches-local ]; then
    #exec ../branches-local "$@"
    #exec ../branches-local.808 "$@"
    exec ../branches-local.bak "$@"
fi