openjdk7 fails to build openjdk7 (on 10.0)

[Jan Henrik Sylvester]

Trying to update openjdk7 via portmaster on 10.0-RC1/amd64, I got a
build failure.

Building openjdk7 with bootstrap-openjdk works (after deleting openjdk7).

Now that I have the latest openjdk7 installed (7.45.18) and
bootstrap-openjdk removed again, building openjdk7 fails again, for
example with this:

# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x000000002daaa365, pid=14901, tid=784661504
#
# JRE version: OpenJDK Runtime Environment (7.0-b18) (build 1.7.0_45-b18)
# Java VM: OpenJDK 64-Bit Server VM (24.45-b08 mixed mode bsd-amd64
compressed oops)
# Problematic frame:
# V  [libjvm.so+0x6aa365]  JVM_FindSignal+0xbbd15
#
# Core dump written. Default location: /cores/core or core.14901
#
# An error report file with more information is saved as:
# /usr/ports/java/openjdk7/work/openjdk/langtools/make/hs_err_pid14901.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp

It is not consistent where the build fails, but it always happens very
early.

Is openjdk7 corrupted or is compiling openjdk7 only supported with
bootstrap-openjdk?

Thanks,
Jan Henrik