RuntimeError when importing an older revision of a YANG file

[andrjohn]

When a YANG file imports another module with a revision date but a newer revision is available in the YANG repository then pyangbind raises a RuntimeError. This is easily reproducible with some trivial YANG files:

(venv)%  pyang --plugindir $PYBINDPLUGIN -f pybind -o binding.py example@2023-04-27.yang 
Traceback (most recent call last):
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/bin/pyang", line 580, in <module>
    run()
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/bin/pyang", line 549, in run
    emit_obj.emit(ctx, modules, fd)
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/lib/python3.10/site-packages/pyangbind/plugin/pybind.py", line 222, in emit
    build_pybind(ctx, modules, fd)
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/lib/python3.10/site-packages/pyangbind/plugin/pybind.py", line 406, in build_pybind
    build_identities(ctx, defn['identity'])
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/lib/python3.10/site-packages/pyangbind/plugin/pybind.py", line 446, in build_identities
    idstore.build_store_from_definitions(ctx, defnd)
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/lib/python3.10/site-packages/pyangbind/helpers/identity.py", line 75, in build_store_from_definitions
    mod_ref_prefixes = module_import_prefixes(ctx)
  File "/Users/anjohnso/Development/cirrus/cirrus-bundles/venv2/lib/python3.10/site-packages/pyangbind/helpers/misc.py", line 24, in module_import_prefixes
    for mod in ctx.modules:
RuntimeError: dictionary changed size during iteration
(venv)% 

example@2023-04-27.yang

module example {
  namespace "urn:example:example";
  prefix ex;

  import common {
    prefix cmn;
    revision-date "2023-04-27";
  }

  revision 2023-04-27;

  leaf name {
    type cmn:identifier;
  }
}

common@2023-04-27.yang

module common {
  namespace "urn:example:common";
  prefix cmn;

  revision 2023-04-27;

  typedef identifier {
    type string;
  }
}

common@2023-04-28.yang

module common {
  namespace "urn:example:common";
  prefix cmn;

  revision 2023-04-28;
  revision 2023-04-27;

  typedef identifier {
    type string;
  }

  typedef value {
    type int16;
  }
}

[JoseIgnacioTamayo]

Hi there,

I was playing a bit with this issue. I guess I found the reason for the Exception, will come back with some updates after.