[ACS41][REQUEST] 5646f5e9772380cc91a8ccb9894c8ed05ffc891f

[Wido den Hollander]

Hi,

I'd like to have 5646f5e9772380cc91a8ccb9894c8ed05ffc891f cherry-picked 
into 4.1

It fixes an issue of attaching RBD volumes to a running instance.

Wido