pre-commit · Sean-Kenneth-Doherty · May 17, 2026
diff --git a/pre_commit/commands/hook_impl.py b/pre_commit/commands/hook_impl.py
@@ -12,6 +12,8 @@
 from pre_commit.store import Store
 
 Z40 = '0' * 40
+Z64 = '0' * 64
+ZERO_OIDS = frozenset((Z40, Z64))
 
 
 def _run_legacy(
@@ -117,6 +119,10 @@ def _rev_exists(rev: str) -> bool:
     return not subprocess.call(('git', 'rev-list', '--quiet', rev))
 
 
+def _is_zero_oid(oid: str) -> bool:
+    return oid in ZERO_OIDS
+
+
 def _pre_push_ns(
         color: bool,
         args: Sequence[str],
@@ -128,9 +134,9 @@ def _pre_push_ns(
     for line in stdin.decode().splitlines():
         parts = line.rsplit(maxsplit=3)
         local_branch, local_sha, remote_branch, remote_sha = parts
-        if local_sha == Z40:
+        if _is_zero_oid(local_sha):
             continue
-        elif remote_sha != Z40 and _rev_exists(remote_sha):
+        elif not _is_zero_oid(remote_sha) and _rev_exists(remote_sha):
             return _ns(
                 'pre-push', color,
                 from_ref=remote_sha, to_ref=local_sha,

diff --git a/tests/commands/hook_impl_test.py b/tests/commands/hook_impl_test.py
@@ -347,6 +347,17 @@ def test_run_ns_pre_push_deleting_branch(push_example):
     assert ns is None
 
 
+def test_run_ns_pre_push_deleting_branch_sha256(push_example):
+    src, src_head, clone, _ = push_example
+
+    with cwd(clone):
+        args = ('origen', src)
+        stdin = f'(delete) {hook_impl.Z64} refs/heads/b {src_head}'.encode()
+        ns = hook_impl._run_ns('pre-push', False, args, stdin)
+
+    assert ns is None
+
+
 def test_hook_impl_main_noop_pre_push(cap_out, store, push_example):
     src, src_head, clone, _ = push_example