Hi again, I just learned about `start_dir`, and the following seems to work:
('ESMpy', '7.1.0r', {
'source_tmpl': 'esmf_7_1_0r_src.tar.gz',
'source_urls':
['http://www.earthsystemmodeling.org/esmf_releases/public/ESMF_7_1_0r/'],
'checksums':
['ae9a5edb8d40ae97a35cbd4bd00b77061f995c77c43d36334dbb95c18b00a889'],
'start_dir': 'src/addon/ESMPy/',
'modulename': 'ESMF',
}),
Sorry for the noise!
Cheers, Andreas

