cbd64b6175
Strictly speaking, we only need sync calls at the end of the script that is directly invoked by nodepool. But just so we don't have to think about it too much, add them to all prepare scripts. Without it, clouds will happily snapshot a system without all the data written to disk! Closes-Bug: 1282136 Change-Id: Id7dcf6667d6e48eb5ae95fd42b09f0651eeb38f9