CA-227145: Call precheck script in extension.
CA-227145: Call precheck script in extension.

To ensure precheck can run more than once and return
the expected output, the precheck script should be
called in extension.

Signed-off-by: Hui Zhang <1290dea41121f0a9caa715ba0808e38da438ab06@citrix.com>

srowe/xen-api,srowe/xen-api,Frezzle/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api,thomassa/xen-api,euanh/xen-api,thomassa/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,Frezzle/xen-api,Frezzle/xen-api,euanh/xen-api,euanh/xen-api,thomassa/xen-api,thomassa/xen-api,thomassa/xen-api,Frezzle/xen-api,thomassa/xen-api