The jdi tests are fairly unstable. See linked bugs. For this reason, we have decided to move them out of the "core" testset, so they will no longer by run by the nightly build or by typical developer JPRT jobs.
It is still possible to run the jdi tests by specifying "-testset all -onlytargets '.*jdk_jdi.*'" on the JPRT command line, or by invoking "make jdk_jdi" from within the TOP/jdk/test directory.