Python 3.7: 4 syntax errors and 33 undefined names

[cclauss]

#2025 accidentally closed #1992 without running the test to see if the work was complete.

The four Python 3.7 syntax errors are discussed in #1994.

flake8 testing of https://github.com/aiidateam/aiida_core on Python 3.7.0

$ flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics

./.ci/test_daemon.py:77:62: F821 undefined name 'e'
        print("Note: the command failed, message: {}".format(e))
                                                             ^
./.ci/test_daemon.py:243:35: F821 undefined name 'CalculationFactory'
    TemplatereplacerCalculation = CalculationFactory('simpleplugins.templatereplacer')
                                  ^
./.ci/test_daemon.py:294:12: F821 undefined name 'Code'
    code = Code.get_from_string(codename)
           ^
./examples/wf_submission/wf_XTiO3_example.py:29:11: F821 undefined name 'DataFactory'
UpfData = DataFactory('upf')
          ^
./examples/wf_submission/wf_XTiO3_example.py:60:8: F821 undefined name 'NotExistent'
except NotExistent:
       ^
./examples/wf_submission/wf_XTiO3_example.py:67:17: F821 undefined name 'DataFactory'
ParameterData = DataFactory('parameter')
                ^
./examples/work/scratch.py:55:44: F821 undefined name 'StructureData'
        spec.input("structure", valid_type=StructureData)
                                           ^
./examples/work/scratch.py:72:28: F821 undefined name 'Calc'
        return ToContext(r=Calc(1234), s=Outputs(1234))
                           ^
./examples/work/scratch.py:86:44: F821 undefined name 'StructureData'
        spec.input("structure", valid_type=StructureData)
                                           ^
./examples/work/scratch.py:101:33: F821 undefined name 'Calc'
            self.insert_barrier(Calc(pid))
                                ^
./examples/work/scratch.py:105:25: F821 undefined name 'load_node'
            self.out(s, load_node(pid)['output_parameters'].dict)
                        ^
./aiida/common/orbital/__init__.py:170:12: F821 undefined name 'BaseFactory'
    return BaseFactory('aiida.common.orbital', entry_point)
           ^
./aiida/work/rmq.py:375:32: E999 SyntaxError: invalid syntax
        self._communicator.await(action, timeout=self.timeout)
                               ^
./aiida/backends/sqlalchemy/models/workflow.py:240:24: F821 undefined name 'model'
            instance = model(**params)
                       ^
./aiida/backends/sqlalchemy/models/workflow.py:241:13: F821 undefined name 'session'
            session.add(instance)
            ^
./aiida/backends/djsite/db/models.py:975:38: F821 undefined name 'e'
            exc.original_exception = e
                                     ^
./aiida/backends/djsite/db/models.py:1114:38: F821 undefined name 'e'
            exc.original_exception = e
                                     ^
./aiida/backends/tests/nodes.py:1377:44: F821 undefined name 'long'
            a3 = Node.get_subclass_from_pk(long(a1.id))
                                           ^
./aiida/backends/tests/work/test_workfunctions.py:145:34: F821 undefined name 'INPUT'
        KWARGS_INPUT = {'b': Int(INPUT)}
                                 ^
./aiida/backends/tests/orm/data/remote.py:52:27: F821 undefined name 'the_path'
                os.remove(the_path)
                          ^
./aiida/utils/queries.py:55:15: F821 undefined name 'InputValidationError'
        raise InputValidationError(
              ^
./aiida/utils/cli/__init__.py:24:9: F821 undefined name 'func'
        func(*args, **kwargs)
        ^
./aiida/utils/cli/__init__.py:24:15: F821 undefined name 'args'
        func(*args, **kwargs)
              ^
./aiida/utils/cli/__init__.py:24:23: F821 undefined name 'kwargs'
        func(*args, **kwargs)
                      ^
./aiida/restapi/translator/data/kpoints.py:137:38: F821 undefined name 'old_label'
                        path.append([old_label, label])
                                     ^
./aiida/orm/importexport.py:2568:39: F821 undefined name 'filename'
                self._zipfile.getinfo(filename)
                                      ^
./aiida/orm/importexport.py:2574:21: F821 undefined name 'filename'
                    filename))
                    ^
./aiida/orm/querybuilder.py:391:45: F821 undefined name 'ormclass'
                    if ormclassifiers[2] != ormclass:
                                            ^
./aiida/orm/querybuilder.py:801:20: F821 undefined name 'edge_exists'
                if edge_exists:
                   ^
./aiida/orm/querybuilder.py:906:72: F821 undefined name 'k'
                                    "".format(', '.join(allowed_keys), k)
                                                                       ^
./aiida/orm/querybuilder.py:1751:37: F821 undefined name 'val'
                        '{}'.format(val, self._tag_to_alias_map.keys())
                                    ^
./aiida/orm/querybuilder.py:1781:23: F821 undefined name 'replacement_dict'
                inp = replacement_dict.get(inp, inp)
                      ^
./aiida/orm/data/array/trajectory.py:203:22: F821 undefined name 'e'
                type(e).__name__, exc))
                     ^
./aiida/scheduler/plugins/direct.py:152:48: F821 undefined name 'virtualMemoryKb'
            lines.append("ulimit -v {}".format(virtualMemoryKb))
                                               ^
./aiida/cmdline/commands/cmd_calculation.py:374:54: E999 SyntaxError: invalid syntax
            result = control_panel._communicator.await(future[1])
                                                     ^
./aiida/cmdline/commands/cmd_work.py:315:26: E999 SyntaxError: invalid syntax
        communicator.await()
                         ^
./aiida/cmdline/commands/cmd_process.py:163:26: E999 SyntaxError: invalid syntax
        communicator.await()
                         ^
4     E999 SyntaxError: invalid syntax
33    F821 undefined name 'e'
37