Revert "Fix race conditions between imagebackend and imagecache"

This reverts commit 2593469103aa7d9d2bcb759b78d5f8637911a1e0

This is a possible cause for bug #1273556

Change-Id: I675806a21bd2e2ab438913690438b2d25b145f7c
Merge "Revert "Fix race conditions between imagebackend and imagecache""