Refine at-sign rev parsing fix

Agent-Logs-Url: https://github.com/gitpython-developers/GitPython/sessions/0273e08f-ead0-4b1e-b148-b103851caca9

Co-authored-by: Byron <63622+Byron@users.noreply.github.com>

Author: Copilot

git/repo/fun.py

@@ -266,16 +266,15 @@ def rev_parse(repo: "Repo", rev: str) -> AnyGitObject:
     parsed_to = 0
     lr = len(rev)
     while start < lr:
+        at_points_to_reflog = False
         if rev[start] not in "^~:@":
             start += 1
             continue
         if rev[start] == "@":
             next_char = rev[start + 1] if start + 1 < lr else None
-            if start == 0:
-                if next_char not in (None, "{", "^", "~", ":"):
-                    start += 1
-                    continue
-            elif next_char != "{":
+            at_points_to_reflog = next_char == "{"
+            is_head_shorthand = start == 0 and next_char in (None, "^", "~", ":")
+            if not (at_points_to_reflog or is_head_shorthand):
                 start += 1
                 continue
         # END handle start
@@ -301,7 +300,7 @@ def rev_parse(repo: "Repo", rev: str) -> AnyGitObject:
 
         start += 1
 
-        if token == "@" and (start >= lr or rev[start] != "{"):
+        if token == "@" and not at_points_to_reflog:
             obj = cast(AnyGitObject, ref.commit)
             ref = None
             parsed_to = start

test/test_repo.py

@@ -159,6 +159,7 @@ def test_commit_from_tag_starting_with_at(self, rw_dir):
         commit = repo.index.commit("init")
         repo.create_tag("@foo")
 
+        self.assertEqual(repo.tags["@foo"].commit, commit)
         self.assertEqual(repo.commit("@"), commit)
         self.assertEqual(repo.commit("@foo"), commit)