Fix Version.__eq__ crashing when compared with a non-Version object

The fallthrough guard only handled falsy operands, so comparing a Version
to any truthy non-Version (a plain tuple with matching arity, a string,
an int) raised AttributeError when trying to read other.tag. Replace the
guard with an isinstance check returning False — Version equality is
domain-specific (tag has precedence over branch/revision) and should
not silently fall back to tuple equality. Add an explicit __hash__ to
keep the class hashable under pyright's static rules.

https://claude.ai/code/session_01KKvrvnVvsBChohuxbRRmzA

Author: claude

CHANGELOG.rst

@@ -2,6 +2,7 @@ Release 0.14.1 (unreleased)
 ===========================
 
 * Fix ``dfetch import`` mangling the namespace of a generic VCS URL whose path contains ``.git`` other than as a suffix
+* Fix ``Version`` comparison raising ``AttributeError`` when compared against a non-``Version`` object
 
 Release 0.14.0 (released 2026-06-14)
 ===========================

dfetch/manifest/version.py

@@ -16,14 +16,18 @@ class Version(NamedTuple):
 
     def __eq__(self, other: Any) -> bool:
         """Check if two versions can be considered as equal."""
-        if not other:
+        if not isinstance(other, Version):
             return False
 
         if self.tag or other.tag:
             return bool(self.tag == other.tag)
 
         return bool(self.branch == other.branch and self.revision == other.revision)
 
+    def __hash__(self) -> int:
+        """Hash based on the underlying tuple value."""
+        return tuple.__hash__(self)
+
     @property
     def field(self) -> tuple[str, str]:
         """Return ``(kind, value)`` for the active field: tag, revision, or branch."""

tests/test_project_version.py

@@ -202,3 +202,22 @@
 def test_version_comparison(name, version_1, version_2, expected_equality):
     actual_equality = version_1 == version_2
     assert actual_equality == expected_equality
+
+
+@pytest.mark.parametrize(
+    "other",
+    [
+        ("", "main", "123"),  # a plain tuple
+        "main",  # a string
+        42,  # an int
+    ],
+)
+def test_version_comparison_with_non_version(other):
+    """Comparing a Version with a non-Version must not crash."""
+    assert (Version(branch="main", revision="123") == other) is False
+
+
+def test_version_remains_hashable():
+    """Defining __eq__ must not break hashing/set membership."""
+    version = Version(tag="1.0")
+    assert version in {version}