From dd6f7faaa3a5242214a350e91fda41a0832d7535 Mon Sep 17 00:00:00 2001
From: marko1olo <barsukdana@gmail.com>
Date: Sat, 6 Jun 2026 10:28:14 +0400
Subject: [PATCH] Handle SHA-256 zero OIDs in pre-push

---
 pre_commit/commands/hook_impl.py |  8 ++++++--
 tests/commands/hook_impl_test.py | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/pre_commit/commands/hook_impl.py b/pre_commit/commands/hook_impl.py
index 7b806f3b8..6affccd50 100644
--- a/pre_commit/commands/hook_impl.py
+++ b/pre_commit/commands/hook_impl.py
@@ -14,6 +14,10 @@
 Z40 = '0' * 40
 
 
+def _is_zero_oid(oid: str) -> bool:
+    return len(oid) in {40, 64} and oid == '0' * len(oid)
+
+
 def _run_legacy(
         hook_type: str,
         hook_dir: str | None,
@@ -128,9 +132,9 @@ 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
index 9aa93af53..cc77e919d 100644
--- a/tests/commands/hook_impl_test.py
+++ b/tests/commands/hook_impl_test.py
@@ -253,6 +253,14 @@ def test_run_ns_post_checkout():
     assert ns.checkout_type == 'c'
 
 
+def test_is_zero_oid():
+    assert hook_impl._is_zero_oid(hook_impl.Z40)
+    assert hook_impl._is_zero_oid('0' * 64)
+    assert not hook_impl._is_zero_oid('0' * 39)
+    assert not hook_impl._is_zero_oid('0' * 63)
+    assert not hook_impl._is_zero_oid('1'.zfill(40))
+
+
 @pytest.fixture
 def push_example(tempdir_factory):
     src = git_dir(tempdir_factory)
@@ -347,6 +355,17 @@ 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 = ('origin', src)
+        stdin = f'(delete) {"0" * 64} 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