extended.openjdk failure: java/rmi/registry/readTest/readTest.sh : unknown error?

https://ci.adoptopenjdk.net/job/Test_openjdk8_j9_extended.openjdk_x86-64_linux/25/consoleFull
Hotspot and OpenJ9:
```
12:30:22 openjdk version "1.8.0_292"
12:30:22 OpenJDK Runtime Environment (build 1.8.0_292-202103091156-b05)
12:30:22 Eclipse OpenJ9 VM (build openj9-0.26.0-m1, JRE 1.8.0 Linux amd64-64-Bit Compressed References 20210309_972 (JIT enabled, AOT enabled)
12:30:22 OpenJ9 - b227feba2
12:30:22 OMR - 4665e2f72
12:30:22 JCL - 1780cbc92b based on jdk8u292-b05)
```
```
13:24:56 TEST: java/rmi/registry/readTest/readTest.sh
13:24:56 TEST JDK: /home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdkbinary/j2sdk-image
13:24:56
13:24:56 ACTION: build -- Passed. All files up to date
13:24:56 REASON: User specified action: run build TestLibrary
13:24:56 TIME: 0.0 seconds
13:24:56 messages:
13:24:56 command: build TestLibrary
13:24:56 reason: User specified action: run build TestLibrary
13:24:56 elapsed time (seconds): 0.0
13:24:56
13:24:56 ACTION: shell -- Failed. Execution failed: exit code 1
13:24:56 REASON: User specified action: run shell readTest.sh
13:24:56 TIME: 37.995 seconds
13:24:56 messages:
13:24:56 command: shell readTest.sh
13:24:56 reason: User specified action: run shell readTest.sh
13:24:56 elapsed time (seconds): 37.995
13:24:56 STDOUT:
13:24:56 Test output :
13:24:56 ==============
13:24:56 rmiregistry output :
13:24:56 ==============
13:24:56 Failed
13:24:56 STDERR:
13:24:56 rerun:
13:24:56 cd /home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/TKG/output_16152931037345/jdk_rmi_1/work/java/rmi/registry/readTest/readTest && \
13:24:56 DISPLAY=:0 \
13:24:56 HOME=/home/jenkins \
13:24:56 PATH=/bin:/usr/bin:/usr/sbin \
13:24:56 TESTFILE=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/rmi/registry/readTest/readTest.sh \
13:24:56 TESTSRC=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/rmi/registry/readTest \
13:24:56 TESTSRCPATH=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/rmi/registry/readTest:/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/rmi/testlibrary \
13:24:56 TESTCLASSES=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/TKG/output_16152931037345/jdk_rmi_1/work/classes/10/java/rmi/registry/readTest \
13:24:56 TESTCLASSPATH=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/TKG/output_16152931037345/jdk_rmi_1/work/classes/10/java/rmi/registry/readTest:/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/TKG/output_16152931037345/jdk_rmi_1/work/classes/10/java/rmi/testlibrary \
13:24:56 COMPILEJAVA=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdkbinary/j2sdk-image \
13:24:56 TESTJAVA=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdkbinary/j2sdk-image \
13:24:56 TESTVMOPTS='-ea -esa -Xmx512m -XX:-UseCompressedOops' \
13:24:56 TESTTOOLVMOPTS='-J-ea -J-esa -J-Xmx512m -J-XX:-UseCompressedOops' \
13:24:56 TESTJAVACOPTS= \
13:24:56 TESTJAVAOPTS= \
13:24:56 TESTTIMEOUTFACTOR=8.0 \
13:24:56 TESTROOT=/home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test \
13:24:56 FS=/ \
13:24:56 PS=: \
13:24:56 NULL=/dev/null \
13:24:56 sh \
13:24:56 /home/jenkins/workspace/Test_openjdk8_j9_extended.openjdk_x86-64_linux/openjdk-tests/openjdk/openjdk-jdk/jdk/test/java/rmi/registry/readTest/readTest.sh
13:24:56
13:24:56 TEST RESULT: Failed. Execution failed: exit code 1
```

Start with java/rmi/registry/readTest/readTest.sh and rerun it using the OpenJDK/OpenJ9 environment recorded in the console log. Inspect the rmiregistry output and the exit-code-1 failure; done means identifying the cause and restoring a passing test.

Written by the indexing model from the issue text.