Resolve invalid python version constraint

Author: rusty

poetry/core/packages/dependency.py

@@ -276,6 +276,7 @@ def to_pep_508(self, with_extras: bool = True) -> str:
     def _create_nested_marker(
         self, name: str, constraint: Union["BaseConstraint", "VersionTypes"]
     ) -> str:
+        from poetry.core.semver.empty_constraint import EmptyConstraint
         from poetry.core.semver.version import Version
         from poetry.core.semver.version_union import VersionUnion
 
@@ -318,6 +319,8 @@ def _create_nested_marker(
                 name = "python_full_version"
 
             marker = '{} == "{}"'.format(name, constraint.text)
+        elif isinstance(constraint, EmptyConstraint):
+            marker = ""
         else:
             if constraint.min is not None:
                 min_name = name

tests/packages/test_main.py

@@ -272,3 +272,12 @@ def test_dependency_from_pep_508_should_not_produce_empty_constraints_for_correc
         str(dep.marker)
         == 'platform_python_implementation != "PyPy" and python_version <= "3.10" and python_version > "3"'
     )
+
+
+def test_dependency_from_pep_508_with_invalid_python_version_constraint():
+    name = 'some-dependency ; python_version >= "3.6" and python_version <= "3.4"'
+    dep = Dependency.create_from_pep_508(name)
+
+    assert dep.name == "some-dependency"
+    assert str(dep.constraint) == "*"
+    assert dep.python_versions == "*"