"--enable-thread-safety" fails on snapshot version

I tried to configure with "--enable-thread-safety" the snapshot
version and it fails with:

"This platform is not thread-safe. Check the file 'config.log'for the
exact reason."

After digging in config.log, the error turns out to be the lack of the
a test file:

conftest.c:144:43: ./src/test/thread/thread_test.c: No such file or directory

Actually the whole src/test directory is missing from the snapshot
versions. After copying it over from my stable version (8.2.3), it
configures fine. Is this is an accidental omission or deliberate ?

Thanks,

George

--
"If I have been able to see further, it was only because I stood on
the shoulders of million monkeys."