Merge branch '3.1.x'

diff --cc src/jinja2/loaders.py
index 5927320cd0744fa7f8e44fb6499355cc984b8002,32f3a74e7d912ace28c4eee0e4c231c989c2c93c..57b55823087332ffbd4d76e738a35e6c64550d5a
--- 1/src/jinja2/loaders.py
--- 2/src/jinja2/loaders.py
+++ b/src/jinja2/loaders.py
@@@ -386,13 -386,16 +386,13 @@@ class PackageLoader(BaseLoader)
                  )
  
              # Package is a zip file.
 -            prefix = (
 -                self._template_root[len(self._archive) :].lstrip(os.path.sep)
 -                + os.path.sep
 -            )
 +            prefix = self._template_root[len(self._archive) :].lstrip(os.sep) + os.sep
              offset = len(prefix)
  
-             for name in self._loader._files.keys():  # type: ignore
+             for name in self._loader._files.keys():
                  # Find names under the templates directory that aren't directories.
 -                if name.startswith(prefix) and name[-1] != os.path.sep:
 -                    results.append(name[offset:].replace(os.path.sep, "/"))
 +                if name.startswith(prefix) and name[-1] != os.sep:
 +                    results.append(name[offset:].replace(os.sep, "/"))
  
          results.sort()
          return results