findbugs: assigned value never used

Assigning Guid.Empty to vmToAttach, but it never used.
We override this value in the next statement.

findbugs code:
DLS: Dead store to local variable that shadows field

Change-Id: I42dd82224a31840157cfcbd499e91f607830bc06
Signed-off-by: Shahar Havivi <shavivi@redhat.com>