This fix for CR 6454676 (Need -XX:+HeapDumpOnCtrlBreak to trigger heap dump on ctrl-break or ctrl-\\) was made available in 1.4.2_18 and 5.0u14. But a format string used in this fix got currupted due to SCCS mis-interpretation and caused the following bug.
6615248: SCCS tag interpetation makes code invalid
And due to this regression, HeapDumpOnCtrlBreak does not work correctly in 5.0u14. This problem has been fixed in 1.4.2_18 and 5.0u17.