From d2bf9e8c6343acdb3791072f79235f94789a6d3b Mon Sep 17 00:00:00 2001
From: Steve Binkowski <binkowsk@nysenate.gov>
Date: Wed, 28 Sep 2016 12:37:48 -0400
Subject: [PATCH] Find common ancestor of two branches

---
 README.md | 6 ++++++
 tips.json | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/README.md b/README.md
index 08fea5b..171d9a0 100644
--- a/README.md
+++ b/README.md
@@ -142,6 +142,7 @@ P.S: All these commands are tested on `git version 2.7.4 (Apple Git-66)`.
 * [Add object notes](#add-object-notes)
 * [Show all the git-notes](#show-all-the-git-notes)
 * [Apply commit from another repository](#apply-commit-from-another-repository)
+* [Find common ancestor of two branches](#find-common-ancestor-of-two-branches)
 
 <!-- Don’t remove or change the comment below – that can break automatic updates. More info at <http://npm.im/doxie.inject>. -->
 <!-- @doxie.inject end toc -->
@@ -960,5 +961,10 @@ git log --show-notes='*'
 git --git-dir=<source-dir>/.git format-patch -k -1 --stdout <SHA1> | git am -3 -k
 ```
 
+## Find common ancestor of two branches
+```sh
+diff -u <(git rev-list --first-parent BranchA) <(git rev-list --first-parent BranchB) | sed -ne 's/^ //p' | head -1
+```
+
 <!-- Don’t remove or change the comment below – that can break automatic updates. More info at <http://npm.im/doxie.inject>. -->
 <!-- @doxie.inject end -->
diff --git a/tips.json b/tips.json
index 89e877a..781e03a 100644
--- a/tips.json
+++ b/tips.json
@@ -414,4 +414,7 @@
 }, {
     "title": "Apply commit from another repository",
     "tip": "git --git-dir=<source-dir>/.git format-patch -k -1 --stdout <SHA1> | git am -3 -k"
+}, {
+    "title": "Find common ancestor of two branches",
+    "tip": "diff -u <(git rev-list --first-parent BranchA) <(git rev-list --first-parent BranchB) | sed -ne 's/^ //p' | head -1"
 }]