Fix double self-dependency (#13366)

The fix itself and its documentation live in pubgrub:
https://github.com/astral-sh/pubgrub/pull/44

Fixes #13344

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/uv/tests/it/pip_compile.rs

@@ -17403,3 +17403,92 @@ fn compile_broken_active_venv() -> Result<()> {
 
     Ok(())
 }
+
+/// <https://github.com/astral-sh/uv/issues/13344>
+#[test]
+fn pubgrub_panic_double_self_dependency() -> Result<()> {
+    let context = TestContext::new("3.12");
+    context
+        .temp_dir
+        .child("pyproject.toml")
+        .write_str(indoc! {r#"
+        [project]
+        name = "foo"
+        version = "0.1.0"
+        dependencies = [
+            "foo",
+            "foo",
+        ]
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+    "#})?;
+
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str(".")?;
+
+    uv_snapshot!(context.filters(), context
+        .pip_compile()
+        .arg(requirements_in.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] [TEMP_DIR]/requirements.in
+    .
+        # via -r requirements.in
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    ");
+
+    Ok(())
+}
+
+/// <https://github.com/astral-sh/uv/issues/13344>
+#[test]
+fn pubgrub_panic_double_self_dependency_extra() -> Result<()> {
+    let context = TestContext::new("3.12");
+    context
+        .temp_dir
+        .child("pyproject.toml")
+        .write_str(indoc! {r#"
+        [project]
+        name = "foo"
+        version = "0.1.0"
+        dependencies = [
+            "foo[test]",
+            "foo[test]",
+        ]
+
+        [project.optional-dependencies]
+        test = ["iniconfig"]
+
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+    "#})?;
+
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str(".")?;
+
+    uv_snapshot!(context.filters(), context
+        .pip_compile()
+        .arg(requirements_in.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] [TEMP_DIR]/requirements.in
+    .
+        # via -r requirements.in
+    iniconfig==2.0.0
+        # via foo
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    ");
+
+    Ok(())
+}