fs: make VDI.similar_content more robust
fs: make VDI.similar_content more robust

xapi-project/message-switch,djs55/message-switch-1,djs55/message-switch,xapi-project/message-switch,djs55/message-switch-1,djs55/message-switch,djs55/message-switch,xapi-project/message-switch,djs55/message-switch-1