FULL PRODUCT VERSION :
output after running make and setting the newly built java as default.latest 9.0.4 used as boot jdk.

openjdk version "10-internal" 2018-03-20
OpenJDK Runtime Environment (build 10-internal+0-adhoc.a.jdk10)
OpenJDK Server VM (build 10-internal+0-adhoc.a.jdk10, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux aHC1a 4.9.61-odroidxu4 #2 SMP PREEMPT Wed Nov 22 16:34:23 CET 2017 armv7l GNU/Linux

A DESCRIPTION OF THE PROBLEM :
Building from sources following the docs at jdk10/README

make works and produces working java binaries. make images does not.

cat support_jrtfs_classes__the.BUILD_JRTFS_batch.cmdline
/home/a/jdk/bin/javac -g -J-XX:+UseSerialGC -J-Xms32M -J-Xmx512M -J-XX:TieredStopAtLevel=1 --release 8 -XDignore.symbol.file=true -g -Xlint:all -Werror -implicit:none -d /home/a/jdk10/build/linux-arm-normal-server-release/support/jrtfs_classes @/home/a/jdk10/build/linux-arm-normal-server-release/support/jrtfs_classes/_the.BUILD_JRTFS_batch.tmp

cat support_jrtfs_classes__the.BUILD_JRTFS_batch.log
javac: release version 8 not supported
Usage: javac <options> <source files>
use --help for a list of possible options


REGRESSION. Last worked in version 9.0.4

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Build from source following the docs.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
make images produces no errors
ACTUAL -
make images does not complete

ERROR MESSAGES/STACK TRACES THAT OCCUR :
cat support_jrtfs_classes__the.BUILD_JRTFS_batch.cmdline
/home/a/jdk/bin/javac -g -J-XX:+UseSerialGC -J-Xms32M -J-Xmx512M -J-XX:TieredStopAtLevel=1 --release 8 -XDignore.symbol.file=true -g -Xlint:all -Werror -implicit:none -d /home/a/jdk10/build/linux-arm-normal-server-release/support/jrtfs_classes @/home/a/jdk10/build/linux-arm-normal-server-release/support/jrtfs_classes/_the.BUILD_JRTFS_batch.tmp

cat support_jrtfs_classes__the.BUILD_JRTFS_batch.log
javac: release version 8 not supported
Usage: javac <options> <source files>
use --help for a list of possible options


REPRODUCIBILITY :
This bug can be reproduced always.