This bug affects the following JTREG test:

    java/lang/instrument/IsModifiableClassAgent.java

It fails under MKS like this:
   java.io.IOException: invalid header field
at java.util.jar.Attributes.read(Attributes.java:393)
at java.util.jar.Manifest.read(Manifest.java:182)
at java.util.jar.Manifest.<init>(Manifest.java:52)
at sun.tools.jar.Main.run(Main.java:124)
at sun.tools.jar.Main.main(Main.java:966)
In addition, the tests in the java/lang/instrument/appendToClassLoaderSearch
don't work on CYGWIN.