do not nullify auditable_id
do not nullify auditable_id

git-svn-id: a5ac5d7d7f2c5b26ca6dff99e20aa4bc584d34b2@31 2c0bb46f-6917-0410-8ab9-f4bf1162979e

lrgalego/audited,ZHANGJIE982/audited,ledermann/audited,Datacom/audited,instacart/audited,brandonaaron/acts_as_audited,azanar/audited,collectiveidea/audited,zorab47/acts_as_audited,ajoulie/audited,ConsultingMD/audited,klatunetworks/audited,happio/audited,cfiorini/audited,simplepractice/audited,xuwupeng2000/audited,GhostGroup/audited,airbnb/audited,ontrack/audited,ktheory/acts_as_audited,reenhanced/audited,ishail/audited