RFR: 8268433: serviceability/dcmd/framework/VMVersionTest.java fails with Unable to send object throw not established PipeIO Listener Thread connection

[Alex Menkov]

Main logic of the tests is:

TestProcessLauncher t = ...;
try {
    t.launch();
    .. perform testing ...
} finally {
   t.quit();
}

We have some problem with the tests, but the exception from TestProcessLauncher.quit() masks it.
The failures are very intermittent, so need to fix this excption to get more information about real error.

-------------

Commit messages:
 - IOPipe.quit should check if the pipe is connected

Changes: https://git.openjdk.java.net/jdk/pull/4532/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4532&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268433
  Stats: 9 lines in 2 files changed: 4 ins; 4 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4532.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4532/head:pull/4532

PR: https://git.openjdk.java.net/jdk/pull/4532