[jdk11u-dev] RFR: 8274642: jdk/jshell/CommandCompletionTest.java fails with NoSuchElementException after JDK-8271287

[Martin Doerr]

Clean backport of JDK-8274642 on top of JDK-8271287.

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Depends on: https://git.openjdk.java.net/jdk11u-dev/pull/481

Commit messages:
 - Backport 47262670f371923a704ec521da40010c2a46be5a

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/492/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=492&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274642
  Stats: 8 lines in 1 file changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/492.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/492/head:pull/492

PR: https://git.openjdk.java.net/jdk11u-dev/pull/492