autotest/autotest — pull request #229 by LaneWolf (2012-03-12 15:28:20+00:00)
Title: Disable drive_cache for xen hvm installation

Commit b6bb71130 fix using drive_cache option. However, this is not
supported by xen qemu and so breaks xen hvm installation.

This patch unset drive_cache so it is not used for hvm installation.

Signed-off-by: Miroslav Rezanina