The build fails but suggests it completed.

Ld /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release/_tf.so normal x86_64
cd /Users/devuser/Documents/Projects/_thirdparty/USD
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -target x86_64-apple-macos10.14 -dynamiclib -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -L/Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release -F/Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release -filelist /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/usd.build/Release/_tf.build/Objects-normal/x86_64/_tf.LinkFileList -install_name @rpath/_tf.so -Xlinker -rpath -Xlinker /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release -Xlinker -rpath -Xlinker /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/arch/Release -dynamiclib -Wl,-headerpad_max_install_names /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release/libtf.dylib /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/arch/Release/libarch.dylib /usr/lib/libm.dylib /Users/devuser/Documents/Projects/_thirdparty/stage/homebrew/Frameworks/Python.framework/Versions/2.7/lib/libpython2.7.dylib /Users/devuser/Documents/Projects/_thirdparty/stage/homebrew/lib/libboost_python37.dylib /Users/devuser/Documents/Projects/_thirdparty/stage/homebrew/lib/libtbb.dylib -Xlinker -dependency_info -Xlinker /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/usd.build/Release/_tf.build/Objects-normal/x86_64/_tf_dependency_info.dat -o /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release/_tf.so
Undefined symbols for architecture x86_64:
"boost::python::detail::init_module(char const*, void (*)())", referenced from:
_init_tf in module.o
_initlibtf in module.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

** BUILD FAILED **

The following build commands failed:
Ld /Users/devuser/Documents/Projects/_thirdparty/stage/build/pxr/base/tf/Release/_tf.so normal x86_64
(1 failure)

USD build complete.
To initialize the environment:
source setvars-macos-brew.sh