The mustang build fails intermittently on windows with the following error:

f:/ws/mustang.ws/build/windows-i586f/bin/javac -J-client -J-XX:ThreadStackSize=768 -J-Xms64m -J-Xmx256m -classpath f:/ws/mustang.ws/build/windows-i586f/classes -bootclasspath f:/ws/mustang.ws/build/windows-i586f/lib/jce.jar;f:/ws/mustang.ws/build/windows-i586f/lib/jsse.jar -sourcepath f:/ws/mustang.ws/build/windows-i586f/gensrc;../../../src/windows/classes;../../../src/share/classes -d f:/ws/mustang.ws/build/windows-i586f/classes -encoding ascii -g -source 1.5 -target 6 @f:/ws/mustang.ws/build/windows-i586f/tmp/sun/javax.naming/.classes.list
..\..\..\src\share\classes\javax\security\auth\kerberos\KerberosPrincipal.java:11: package sun.security.krb5 does not exist
import sun.security.krb5.Asn1Exception;
                        ^
..\..\..\src\share\classes\javax\security\auth\kerberos\KerberosPrincipal.java:12: package sun.security.krb5 does not exist
import sun.security.krb5.KrbException;
                        ^
... etc

The full log is attached.

After a few clobber/rebuild iterations the build could succeed.