Current jdk7u-osx workspace doesn't build if ALT_BOOTDIR is set to the latest JDK7 build. The root cause is that "os.arch" system property value is different between Apple JDK6 and Oracle JDK7, x86_64 and amd64 respectively.
Expanding the scope to also cover adjustments to os.name...

< osName.startWith("Mac OS X")
> osName.contains("OS X")

Many of the files overlap and it's convenient to do both as part of the work for this bug.
CCC request approved...

   http://ccc.sfbay/7130404
Simple testcase...

public class P {
  public static void main(String args []) {
    System.out.println(System.getProperty("os.name"));
    System.out.println(System.getProperty("os.arch"));
  }
}

Test passes if the following is written to stdout...

Mac OS X
x86_64