python-timbl suddenly fails to compile on mac? boost-python3 not found

[proycon]

For some unknown reason python-timbl fails to compile on mac (or at least on the travis instance). Despite there having been no changes in python-timbl or LaMachine. Something upstream in homebrew perhaps?

I temporarily made this a non-breaking error so the LaMachine installation continues.

running build_ext

  building 'timblapi' extension

  creating build/temp.macosx-10.13-x86_64-3.7

  creating build/temp.macosx-10.13-x86_64-3.7/src

  clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/Tk.framework/Versions/8.5/Headers -I/usr/local/opt/boost/include -I/usr/local/include -I/usr/local/Cellar/libxml2/2.9.10/include/libxml2 -I/usr/local/include -I/usr/local/opt/openssl@1.1/include -I/usr/local/opt/sqlite/include -I/Users/travis/build/proycon/LaMachine/travis-stable-venv/include -I/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/include/python3.7m -c src/timblapi.cc -o build/temp.macosx-10.13-x86_64-3.7/src/timblapi.o -std=c++11 -stdlib=libc++
  clang++ -bundle -undefined dynamic_lookup build/temp.macosx-10.13-x86_64-3.7/src/timblapi.o -L/usr/local/lib -L/usr/local/opt/boost/lib -L/usr/local/Cellar/libxml2/2.9.10/lib -L/usr/local/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/sqlite/lib -ltimbl -lboost_python -o build/lib.macosx-10.13-x86_64-3.7/timblapi.cpython-37m-darwin.so

  ld: library not found for -lboost_python

  clang: error: linker command failed with exit code 1 (use -v to see invocation)

  error: command 'clang++' failed with exit status 1