provider: fetch optional vcs dependency only if required

src/poetry/puzzle/provider.py

@@ -572,18 +572,6 @@ def complete_package(
             dependency = dependency_package.dependency
             requires = package.requires
 
-        if self._load_deferred:
-            # Retrieving constraints for deferred dependencies
-            for r in requires:
-                if r.is_direct_origin():
-                    locked = self.get_locked(r)
-                    # If lock file contains exactly the same URL and reference
-                    # (commit hash) of dependency as is requested,
-                    # do not analyze it again: nothing could have changed.
-                    if locked is not None and locked.package.is_same_package_as(r):
-                        continue
-                    self.search_for_direct_origin_dependency(r)
-
         optional_dependencies = []
         _dependencies = []
 
@@ -636,6 +624,18 @@ def complete_package(
 
             _dependencies.append(dep)
 
+        if self._load_deferred:
+            # Retrieving constraints for deferred dependencies
+            for dep in _dependencies:
+                if dep.is_direct_origin():
+                    locked = self.get_locked(dep)
+                    # If lock file contains exactly the same URL and reference
+                    # (commit hash) of dependency as is requested,
+                    # do not analyze it again: nothing could have changed.
+                    if locked is not None and locked.package.is_same_package_as(dep):
+                        continue
+                    self.search_for_direct_origin_dependency(dep)
+
         dependencies = self._get_dependencies_with_overrides(
             _dependencies, dependency_package
         )

tests/puzzle/test_provider.py

@@ -716,3 +716,25 @@ def test_complete_package_with_extras_preserves_source_name(
     assert requires[0].source_name == source_name
     assert requires[1].name == "b"
     assert requires[1].source_name is None
+
+
+@pytest.mark.parametrize("with_extra", [False, True])
+def test_complete_package_fetches_optional_vcs_dependency_only_if_requested(
+    provider: Provider, repository: Repository, mocker: MockerFixture, with_extra: bool
+):
+    optional_vcs_dependency = Factory.create_dependency(
+        "demo", {"git": "https://github.com/demo/demo.git", "optional": True}
+    )
+    package = Package("A", "1.0", features=["foo"] if with_extra else [])
+    package.add_dependency(optional_vcs_dependency)
+    package.extras["foo"] = [optional_vcs_dependency]
+    repository.add_package(package)
+
+    spy = mocker.spy(provider, "_search_for_vcs")
+
+    provider.complete_package(DependencyPackage(package.to_dependency(), package))
+
+    if with_extra:
+        spy.assert_called()
+    else:
+        spy.assert_not_called()