The second release candidates for the 1.72.0 release are now available at:

<https://dl.bintray.com/boostorg/release/1.72.0/source/>

I have built this candidate with the following configurations:
    Mac OS 10.14.6 with Apple LLVM version 10.0.1 (clang-1001.0.46.4)
    Successful build with C++03/11/14/17

    Mac OS 10.14.6 with with clang trunk:
    Successful build with C++03/11/14/17/2a