Compiling 298 files for BUILD_jdk.javadoc.interim
Compiling 159 files for BUILD_TOOLS_JDK
Exception in thread "main" java.lang.AssertionError: Could not parse protocol line: >>"HTTP/1.0 500 handshakefailed"<<
at jdk.compiler.interim/com.sun.tools.sjavac.client.SjavacClient.compile(SjavacClient.java:132)
at jdk.compiler.interim/com.sun.tools.sjavac.client.ClientMain.run(ClientMain.java:78)
at jdk.compiler.interim/com.sun.tools.sjavac.client.ClientMain.run(ClientMain.java:49)
at jdk.compiler.interim/com.sun.tools.sjavac.Main.go(Main.java:56)
at jdk.compiler.interim/com.sun.tools.sjavac.Main.main(Main.java:46)
CompileToolsJdk.gmk:45: recipe for target '/Users/guest/Desktop/Java/jdk/build/macosx-x64/buildtools/jdk_tools_classes/_the.BUILD_TOOLS_JDK_batch' failed
make[3]: *** [/Users/guest/Desktop/Java/jdk/build/macosx-x64/buildtools/jdk_tools_classes/_the.BUILD_TOOLS_JDK_batch] Error 1
make/Main.gmk:85: recipe for target 'buildtools-jdk' failed
make[2]: *** [buildtools-jdk] Error 2
make[2]: *** Waiting for unfinished jobs....

build works if you change ENABLE_JAVAC_SERVER to no in the spec.gmk file:

# Enable sjavac support = use a javac server,
# multi core javac compilation and dependency tracking.
ENABLE_SJAVAC:=no
ENABLE_JAVAC_SERVER:=no

java - version of resulting build:

./bin/java -version
openjdk version "10-internal"
OpenJDK Runtime Environment (build 10-internal+0-2017-12-08-1656510.guest.jdk)
OpenJDK 64-Bit Server VM (build 10-internal+0-2017-12-08-1656510.guest.jdk, mixed mode)

configuration built with jib
[jib LOG] Bootstrapping com.oracle.java.jib jib 3.0-SNAPSHOT 94d9866