Segmentation Fault after installation on OSX

I'm building OpenVDB so I can use `pyopenvdb` on OSX Catalina.  I'd like to use it in an anaconda environment (not using a system Python).  After configuring, building, and installing, I get the following error (build details below):

```

(base) hage581@localhost build % python

Python 3.7.4 (default, Aug 13 2019, 15:17:50) 

[Clang 4.0.1 (tags/RELEASE_401/final)] :: Anaconda, Inc. on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> import pyopenvdb

zsh: segmentation fault  python

```



I build release 7.1.0 using the install file:

```

# Clean the directory except for this file

find . -type f -not -name 'install.sh' -print0 | xargs -0 rm -r --

# run cmake with all the nice options

cmake ../ \

    -D CMAKE_PREFIX_PATH=/opt/anaconda/miniconda/ \

    -D CMAKE_INSTALL_PREFIX=/opt/anaconda/miniconda/ \

    -D OPENVDB_BUILD_PYTHON_MODULE=ON \

    -D Python_FIND_STRATEGY=LOCATION \

    -D Python_ROOT=/opt/anaconda/miniconda/ \

    -D BOOST_ROOT=/opt/anaconda/miniconda/ \

    -D Boost_NO_SYSTEM_PATHS=ON #--trace

# actually compile

make -j4

make install

```

which generates the following output:

```

-- The CXX compiler identification is AppleClang 12.0.0.12000032

-- Detecting CXX compiler ABI info

-- Detecting CXX compiler ABI info - done

-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped

-- Detecting CXX compile features

-- Detecting CXX compile features - done

-- Using ccache: /usr/local/bin/ccache

-- CMake Build Type: Release

-- Configuring for OpenVDB Version 7.1.0

-- Configuring for OpenVDB ABI Version 7

-- ----------------------------------------------------

-- ------------- Configuring OpenVDBCore --------------

-- ----------------------------------------------------

-- Found PkgConfig: /usr/local/bin/pkg-config (found version "0.29.2") 

-- Found IlmBase: /usr/local/include/OpenEXR (found suitable version "2.5", minimum required is "2.2") found components: Half 

-- Found TBB: /usr/local/include (found suitable version "2020.3", minimum required is "2017.0") found components: tbb 

-- Found ZLIB: /opt/anaconda/miniconda/lib/libz.dylib (found suitable version "1.2.11", minimum required is "1.2.7") 

-- Found Blosc: /opt/anaconda/miniconda/lib/libblosc.dylib (found suitable version "1.20.1", minimum required is "1.5.0") 

CMake Warning at openvdb/CMakeLists.txt:89 (message):

  The version of Blosc located is greater than 1.5.0.  There have been

  reported issues with using later versions of Blosc with OpenVDB.  OpenVDB

  has been tested fully against Blosc 1.5.0, it is recommended that you use

  this version where possible.





-- Found Boost: /opt/anaconda/miniconda/include (found suitable version "1.67.0", minimum required is "1.61") found components: iostreams system regex 

-- Looking for C++ include pthread.h

-- Looking for C++ include pthread.h - found

-- Performing Test CMAKE_HAVE_LIBC_PTHREAD

-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success

-- Found Threads: TRUE  

-- ----------------------------------------------------

-- ------------ Configuring OpenVDBPython -------------

-- ----------------------------------------------------

-- Found Python: /opt/anaconda/miniconda/include/python3.7m) (found suitable version "3.7.4", minimum required is "2.7")

-- Found boost_python37

-- ----------------------------------------------------

-- ----------- Configuring OpenVDBBinaries ------------

-- ----------------------------------------------------

-- Found TBB: /usr/local/include (found suitable version "2020.3", minimum required is "2017.0") found components: tbbmalloc 

-- Configuring done

-- Generating done

-- Build files have been written to: /Users/hage581/util/openvdb/build

```

and successfully builds and installs, with the exception of these interesting lines:

```

[ 82%] Linking CXX shared library libopenvdb.dylib

[ 83%] Linking CXX static library libopenvdb.a

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libopenvdb.a(Platform.cc.o) has no symbols

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libopenvdb.a(Platform.cc.o) has no symbols

[ 83%] Built target openvdb_shared

```



Any idea what's happening?

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