There can be only one...

packages/py-spinnfrontendcommon/package.py

@@ -34,6 +34,6 @@ class PySpinnfrontendcommon(PythonPackage):
         super(PySpinnfrontendcommon, self).install(spec, prefix)
         # Work out the python version installed, so we know where to put
         # the java code!
-        python_spec = find("python@3.7:")
+        python_spec = find("python@3.7:")[0]
         python_lib = f"python{python_spec.version}"
         install_tree("JavaSpiNNaker", prefix.lib.join(python_lib).site_packages)