Reset def_boot_osid after a node is freed. Stops it from looking for old special kernels that might not exist anymore.
Reset def_boot_osid after a node is freed. Stops it from looking for old special kernels that might not exist anymore.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome