Fix typing issues with delete_head and Remote.add

delete_head and Head.delete historically accept either Head objects
or a str name of a head.  Adjust the typing to match.  This
unfortunately requires suppressing type warnings in the signature of
RemoteReference.delete, since it inherits from Head but does not
accept str (since it needs access to the richer data of
RemoteReference).

Using assignment to make add an alias for create unfortunately
confuses mypy, since it loses track of the fact that it's a
classmethod and starts treating it like a staticmethod.  Replace
with a stub wrapper instead.

Author: rra

Diff for: git/refs/head.py

@@ -129,7 +129,7 @@ class Head(Reference):
     k_config_remote_ref = "merge"           # branch to merge from remote
 
     @classmethod
-    def delete(cls, repo: 'Repo', *heads: 'Head', force: bool = False, **kwargs: Any) -> None:
+    def delete(cls, repo: 'Repo', *heads: 'Union[Head, str]', force: bool = False, **kwargs: Any) -> None:
         """Delete the given heads
 
         :param force:

Diff for: git/refs/remote.py

@@ -37,8 +37,13 @@ def iter_items(cls, repo: 'Repo', common_path: Union[PathLike, None] = None,
         # super is Reference
         return super(RemoteReference, cls).iter_items(repo, common_path)
 
+    # The Head implementation of delete also accepts strs, but this
+    # implementation does not.  mypy doesn't have a way of representing
+    # tightening the types of arguments in subclasses and recommends Any or
+    # "type: ignore".  (See https://github.com/python/typing/issues/241)
     @ classmethod
-    def delete(cls, repo: 'Repo', *refs: 'RemoteReference', **kwargs: Any) -> None:
+    def delete(cls, repo: 'Repo', *refs: 'RemoteReference',  # type: ignore
+               **kwargs: Any) -> None:
         """Delete the given remote references
 
         :note:

Diff for: git/remote.py

@@ -665,7 +665,9 @@ def create(cls, repo: 'Repo', name: str, url: str, **kwargs: Any) -> 'Remote':
         return cls(repo, name)
 
     # add is an alias
-    add = create
+    @ classmethod
+    def add(cls, repo: 'Repo', name: str, url: str, **kwargs: Any) -> 'Remote':
+        return cls.create(repo, name, url, **kwargs)
 
     @ classmethod
     def remove(cls, repo: 'Repo', name: str) -> str:

Diff for: git/repo/base.py

@@ -429,7 +429,7 @@ def create_head(self, path: PathLike, commit: str = 'HEAD',
         :return: newly created Head Reference"""
         return Head.create(self, path, commit, logmsg, force)
 
-    def delete_head(self, *heads: 'Head', **kwargs: Any) -> None:
+    def delete_head(self, *heads: 'Union[str, Head]', **kwargs: Any) -> None:
         """Delete the given heads
 
         :param kwargs: Additional keyword arguments to be passed to git-branch"""