From 7d889b120b4b280ea0bf5daaa546dec067c112e9 Mon Sep 17 00:00:00 2001
From: Scott Worley <scottworley@scottworley.com>
Date: Thu, 9 Apr 2020 21:44:56 -0700
Subject: [PATCH 1/1] Verify old rev is an ancestor of new rev

---
 pinch.py | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/pinch.py b/pinch.py
index 80e631b..774f5f1 100644
--- a/pinch.py
+++ b/pinch.py
@@ -278,6 +278,17 @@ def git_fetch(v: Verification, channel: Channel) -> None:
                               channel.git_ref])
     v.result(process.returncode == 0)
 
+    if hasattr(channel, 'old_git_revision'):
+        v.status('Verifying rev is an ancestor of previous rev %s' % channel.old_git_revision)
+        process = subprocess.run(['git',
+                                  '-C',
+                                  channel.git_cachedir,
+                                  'merge-base',
+                                  '--is-ancestor',
+                                  channel.old_git_revision,
+                                  channel.git_revision])
+        v.result(process.returncode == 0)
+
 
 def compare_tarball_and_git(
         v: Verification,
-- 
2.44.1