[Boost-build] Why is there an extra directory added when installing boost?

Subject: [Boost-build] Why is there an extra directory added when installing boost?
From: Nelson, Jarom (nelson99_at_[hidden])
Date: 2017-01-18 14:39:16

(Windows 7, MSVC 2015)
I'd like to install the boost library and headers to a path, say  D:/third_party.  To do this, I've run
bootstrap.bat --prefix=D:/third_party
followed by
b2 install --prefix=D:/third_party

I would expect boost library binaries to then be installed to:
D:/third_party/lib
And boost headers to:
D:/third_party/include/boost

The library binaries are installed where I expect, however, the headers are installed to:
D:/third_party/include/boost-1_62/boost

I'd rather not have to add the boost-1_62 directory to my include path or manually move folders to remove the extra directory. How can I call b2 with the correct option so that the boost headers are installed to D:/third_party/include/boost?

Jarom Nelson; x33953
Computer Scientist, NIF, LLNL