Thanks for the great project! It unfortunately looks like [setuptools_scm dropped support for Python 2](https://github.com/pypa/setuptools_scm/issues/541), which appears to have broken the install for mpmath on Python 2. Here's a [broken CI run](https://github.com/mikedh/trimesh/pull/1182/checks?check_run_id=2135678957) demonstrating the issue.
Thanks for the great project!
It unfortunately looks like setuptools_scm dropped support for Python 2, which appears to have broken the install for mpmath on Python 2. Here's a broken CI run demonstrating the issue.