colcon build failing on python modules

[zmichaels11]

Version used: 0.24
OS: Ubuntu Bionic x86_64
ROS version: melodic

Steps to reproduce break:

1. install latest colcon from pip
2. create a new workspace
3. clone https://github.com/zmichaels11/test-py-module into workspace
4. run colcon build

This works on version 0.23, which can be acquired from apt.

[zmichaels11]

Error output:

[2.132s] ERROR:colcon.colcon_core.package_identification:Exception in package identification extension 'python_setup_py' in 'src/test-py-module': 'dict' object has no attribute 'name'
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/colcon_core/package_identification/__init__.py", line 143, in _identify
    retval = extension.identify(_reused_descriptor_instance)
  File "/usr/local/lib/python3.6/dist-packages/colcon_python_setup_py/package_identification/python_setup_py.py", line 54, in identify
    name = config['metadata'].name
AttributeError: 'dict' object has no attribute 'name'

Expected output:

colcon build --event-handlers console_direct+
Starting >>> test-py-module
running egg_info                             
creating /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info
writing /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/PKG-INFO
writing dependency_links to /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/dependency_links.txt
writing requirements to /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/requires.txt
writing top-level names to /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/top_level.txt
writing manifest file '/home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/SOURCES.txt'
reading manifest file '/home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/SOURCES.txt'
writing manifest file '/home/ubuntu/ws/build/test-py-module/test_py_module.egg-info/SOURCES.txt'
running build
running build_py
creating /home/ubuntu/ws/build/test-py-module/build
creating /home/ubuntu/ws/build/test-py-module/build/lib
creating /home/ubuntu/ws/build/test-py-module/build/lib/test_py_module
copying test_py_module/__init__.py -> /home/ubuntu/ws/build/test-py-module/build/lib/test_py_module
copying test_py_module/run_annoy.py -> /home/ubuntu/ws/build/test-py-module/build/lib/test_py_module
running install
running install_lib
creating /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module
copying /home/ubuntu/ws/build/test-py-module/build/lib/test_py_module/__init__.py -> /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module
copying /home/ubuntu/ws/build/test-py-module/build/lib/test_py_module/run_annoy.py -> /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module
byte-compiling /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module/__init__.py to __init__.cpython-36.pyc
byte-compiling /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module/run_annoy.py to run_annoy.cpython-36.pyc
running install_egg_info
Copying /home/ubuntu/ws/build/test-py-module/test_py_module.egg-info to /home/ubuntu/ws/install/test-py-module/lib/python3.6/site-packages/test_py_module-0.1-py3.6.egg-info
running install_scripts
writing list of installed files to '/home/ubuntu/ws/build/test-py-module/install.log'
Finished <<< test-py-module [0.64s]          

Summary: 1 package finished [1.03s]

[dirk-thomas]

Please see #32 for the proposed fix.

[zmichaels11]

Testing fix on a clean machine