Resolve invalid python version constraint

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

@@ -254,3 +254,12 @@ def test_dependency_from_pep_508_with_python_full_version_pep440_compatible_rele
     assert dep.name == "pathlib2"
     assert str(dep.constraint) == "*"
     assert dep.python_versions == "~=3.4 || <3"
+
+
+def test_dependency_from_pep_508_with_invalid_python_version_constraint():
+    name = 'pytest-mypy ; python_version < "3.10" and python_version > "3"'
+    dep = Dependency.create_from_pep_508(name)
+
+    assert dep.name == "pytest-mypy"
+    assert str(dep.constraint) == "*"
+    assert dep.python_versions == "<3.10 >=4"