make -j2 aborts with "make[3]: *** read jobs pipe: Success. Stop."

[Dan Kegel]

Porting a particular build of v8 from ubuntu 17.10 to ubuntu 18.04 circa beta 2,
its make failed at -j2, but succeeded at -j1.
The error message was odd:

...
make[3]: Entering directory '/home/buildbot/src/oblong-v8/out/v8/out'
testing/gtest.target.x64.release.mk:229: warning: overriding recipe for target '/home/buildbot/src/oblong-v8/out/v8/out/x64.release/libgtest.a'
testing/gtest.host.x64.release.mk:221: warning: ignoring old recipe for target '/home/buildbot/src/oblong-v8/out/v8/out/x64.release/libgtest.a'
make[3]: Leaving directory '/home/buildbot/src/oblong-v8/out/v8/out'
make[3]: *** read jobs pipe: Success. Stop.
make[3]: *** Waiting for unfinished jobs....
make[3]: Entering directory '/home/buildbot/src/oblong-v8/out/v8/out'
  /home/buildbot/src/oblong-v8/out/v8/third_party/llvm-build/Release+Asserts/bin/clang++ '-DCR_CLANG_REVISION=278861-1'... -c -o /home/buildbot/src/oblong-v8/out/v8/out/x64.release/obj.target/v8_base/src/address-map.o ../src/address-map.cc
make[3]: Leaving directory '/home/buildbot/src/oblong-v8/out/v8/out'
make[3]: *** write jobserver: Bad file descriptor. Stop.
Makefile:318: recipe for target 'x64.release' failed
make[2]: *** [x64.release] Error 2
make[2]: INTERNAL: Exiting with 1 jobserver tokens available; should be 2!
Makefile:48: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/buildbot/src/oblong-v8'
dh_auto_build: make -j8 -O returned exit code 2
debian/rules:10: recipe for target 'build' failed
make: *** [build] Error 25
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2
debuild: fatal error at line 1152:
dpkg-buildpackage -rfakeroot -us -uc -ui -b -j8 failed
...

This is on a machine with 32GB of RAM.

The problem reproduces quickly and reliably. Happy to try other versions of make and/or provide more data.