Move routes stubs to @python2 directory (#5637)

* Move routes stubs to @python2 directory

* Ignore Python-2-only stubs for stubtest

* Use standard idiom for re-exporting items

Co-authored-by: Akuli <akuviljanen17@gmail.com>

tests/stubtest_third_party.py

@@ -8,6 +8,7 @@ import sys
 import tempfile
 import toml
 import venv
+from glob import glob
 from pathlib import Path
 
 
@@ -37,7 +38,7 @@ def run_stubtest(dist: Path) -> None:
         metadata = dict(toml.loads(f.read()))
 
     # Ignore stubs that don't support Python 2
-    if not bool(metadata.get("python3", True)):
+    if not bool(metadata.get("python3", True)) or not has_py3_stubs(dist):
         return
 
     with tempfile.TemporaryDirectory() as tmp:
@@ -105,6 +106,10 @@ def run_stubtest(dist: Path) -> None:
             print(f"stubtest succeeded for {dist.name}", file=sys.stderr)
 
 
+def has_py3_stubs(dist: Path) -> bool:
+    return len(glob(f"{dist}/*.pyi")) > 0 or len(glob(f"{dist}/[!@]*/__init__.pyi")) > 0
+
+
 def main():
     parser = argparse.ArgumentParser()
     parser.add_argument("--num-shards", type=int, default=1)