hg: build-infra/jdk8: In get_souce.sh, prevent hang by preemptive check for locked repositories.

[fredrik.ohrstrom at oracle.com]

Changeset: 4d608b2d7383
Author:    ohrstrom
Date:      2012-09-18 10:53 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/4d608b2d7383

In get_souce.sh, prevent hang by preemptive check for locked repositories.

! get_source.sh
+ make/scripts/verifyforest.sh