empty custom config hangs when loading

[havok2063]

When a custom config file is present but empty, sdsstools hangs when loading. My guess is it's entered into a form of recursive reading loop. I'd expect an empty config file to resolve to a blank dictionary object during merge with its parent in package/etc/xxx.yml

To reproduce:

• create an empty custom config, e.g. ~/.config/sdss/tree.yml
• try to load the config file with sdsstools.get_config("tree")

Traceback upon key interrupt

from sdsstools import get_config, get_logger, get_package_version

config=get_config('tree')
^C---------------------------------------------------------------------------
KeyboardInterrupt                         Traceback (most recent call last)
<ipython-input-2-e5a3198d9f43> in <module>
----> 1 config=get_config('tree')

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in get_config(name, config_file, allow_user, user_path, config_envvar, merge_mode, default_envvars)
    174     if merge_mode == 'update':
    175         return Configuration(custom_config_fn, base_config=config_file,
--> 176                              default_envvars=default_envvars)
    177     else:
    178         return Configuration(custom_config_fn, base_config=None,

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in __init__(self, config, base_config, default_envvars)
    211         __ENVVARS__ = default_envvars
    212
--> 213         self.load(config)
    214
    215     def _parse_config(self, config, use_base=True):

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in load(self, config)
    244             self.CONFIG_FILE = None
    245
--> 246         super().__init__(self._parse_config(config))
    247
    248         # Save name of the configuration file (if the input is a file).

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in _parse_config(self, config, use_base)
    225                 raise ValueError('Invalid config of type {}'.format(type(config)))
    226
--> 227         return merge_config(self._parse_config(config, use_base=False), self._BASE)
    228
    229     def load(self, config=None):

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in _parse_config(self, config, use_base)
    221                 return config
    222             elif isinstance(config, (str, pathlib.Path)):
--> 223                 return read_yaml_file(config)
    224             else:
    225                 raise ValueError('Invalid config of type {}'.format(type(config)))

~/anaconda3/envs/treetest/lib/python3.7/site-packages/sdsstools/configuration.py in read_yaml_file(path, use_extends, loader)
     58         fp.seek(0)
     59         while True:
---> 60             line = fp.readline()
     61             if line.strip().startswith('#!extends'):
     62                 base_file = line.strip().split()[1]

~/anaconda3/envs/treetest/lib/python3.7/codecs.py in decode(self, input, final)
    317         raise NotImplementedError
    318
--> 319     def decode(self, input, final=False):
    320         # decode input (taking the buffer into account)
    321         data = self.buffer + input

KeyboardInterrupt:

[albireox]

Mmm, interesting. It seems this fails because of some come I added to allow extending a YAML from a different YAML. It should be fairly easy to fix and test.

[albireox]

I released this as 0.4.5 if you want to upgrade.