[jdk11u-dev] RFR: 8277328: jdk/jshell/CommandCompletionTest.java failures on Windows

[Goetz Lindenmaier]

We see this bug in 11, too, so I would like to backport this fix.

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Commit messages:
 - Backport 3955b037da8a0981d8efc67f28caaacdef7dfb31

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/757/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=757&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277328
  Stats: 25 lines in 2 files changed: 17 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/757.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/757/head:pull/757

PR: https://git.openjdk.java.net/jdk11u-dev/pull/757