Recurse into build / dist directories

See #12625 for context

Author: root

src/_pytest/main.py

@@ -63,9 +63,7 @@ def pytest_addoption(parser: Parser) -> None:
             "*.egg",
             ".*",
             "_darcs",
-            "build",
             "CVS",
-            "dist",
             "node_modules",
             "venv",
             "{arch}",

testing/test_collection.py

@@ -135,10 +135,19 @@ def test_foo():
 
 
 class TestCollectFS:
+    def test_build_conditional_ignore(self, pytester: Pytester) -> None:
+        tmp_path = pytester.path
+        ensure_file(tmp_path / "build" / "test_found.py")
+        ensure_file(tmp_path / "dist" / "test_found.py")
+        for x in tmp_path.rglob("test_*.py"):
+            x.write_text("def test_hello(): pass", encoding="utf-8")
+
+        result = pytester.runpytest("--collect-only")
+        s = result.stdout.str()
+        assert "test_found" in s
+
     def test_ignored_certain_directories(self, pytester: Pytester) -> None:
         tmp_path = pytester.path
-        ensure_file(tmp_path / "build" / "test_notfound.py")
-        ensure_file(tmp_path / "dist" / "test_notfound.py")
         ensure_file(tmp_path / "_darcs" / "test_notfound.py")
         ensure_file(tmp_path / "CVS" / "test_notfound.py")
         ensure_file(tmp_path / "{arch}" / "test_notfound.py")