pygama install script fails when running build_ext

Running pygama_install.sh within the legend docker container (legendexp/legend-base:latest) fails when running build_ext. To reproduce, change the INSTALL_PREFIX within the script to a valid directory (I used /home/src) and run the script. It seems to be complaining about a missing CMakeLists.txt file in pygama/cygama/pybind11. Here is the error message:

CMake Error at CMakeLists.txt:15 (add_subdirectory):
The source directory

/home/src/pygama/cygama/pybind11

does not contain a CMakeLists.txt file.

CMake Error at CMakeLists.txt:18 (pybind11_add_module):
Unknown CMake command "pybind11_add_module".

-- Configuring incomplete, errors occurred!
See also "/home/src/pygama/build/temp.linux-x86_64-3.7/CMakeFiles/CMakeOutput.log".
Traceback (most recent call last):
File "setup.py", line 82, in
zip_safe=False,
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/init.py", line 145, in setup
return distutils.core.setup(**attrs)
File "/opt/anaconda3/lib/python3.7/distutils/core.py", line 148, in setup
dist.run_commands()
File "/opt/anaconda3/lib/python3.7/distutils/dist.py", line 966, in run_commands
self.run_command(cmd)
File "/opt/anaconda3/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/command/install.py", line 67, in run
self.do_egg_install()
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/command/install.py", line 109, in do_egg_install
self.run_command('bdist_egg')
File "/opt/anaconda3/lib/python3.7/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/opt/anaconda3/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/command/bdist_egg.py", line 172, in run
cmd = self.call_command('install_lib', warn_dir=0)
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/command/bdist_egg.py", line 158, in call_command
self.run_command(cmdname)
File "/opt/anaconda3/lib/python3.7/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/opt/anaconda3/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "/opt/anaconda3/lib/python3.7/site-packages/setuptools/command/install_lib.py", line 11, in run
self.build()
File "/opt/anaconda3/lib/python3.7/distutils/command/install_lib.py", line 107, in build
self.run_command('build_ext')
File "/opt/anaconda3/lib/python3.7/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/opt/anaconda3/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "setup.py", line 38, in run
self.build_extension(ext)
File "setup.py", line 67, in build_extension
cwd=self.build_temp, env=env)
File "/opt/anaconda3/lib/python3.7/subprocess.py", line 347, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['cmake', '/home/src/pygama', '-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/home/src/pygama/build/lib.linux-x86_64-3.7/pygama', '-DPYTHON_EXECUTABLE=/opt/anaconda3/bin/python', '-DCMAKE_BUILD_TYPE=Release']' returned non-zero exit status 1.

Reproduce the failure by running pygama_install.sh in the legendexp/legend-base:latest container with INSTALL_PREFIX set to a valid directory. Inspect setup.py, the top-level CMakeLists.txt, and pygama/cygama/pybind11, then confirm that build_ext completes without the reported missing-file and unknown-command errors.