From 7938af1e084befb63fa079d3569d552ed64a1e58 Mon Sep 17 00:00:00 2001
From: Simon Cropp <simon.cropp@gmail.com>
Date: Fri, 16 Jun 2017 11:14:48 +1000
Subject: [PATCH] add a null check for the merge base

fixes https://github.com/GitTools/GitVersion/issues/1230
---
 src/GitVersionCore/GitRepoMetadataProvider.cs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/GitVersionCore/GitRepoMetadataProvider.cs b/src/GitVersionCore/GitRepoMetadataProvider.cs
index 4b7c8dd914..8ba5c00a0b 100644
--- a/src/GitVersionCore/GitRepoMetadataProvider.cs
+++ b/src/GitVersionCore/GitRepoMetadataProvider.cs
@@ -147,8 +147,14 @@ public Commit FindMergeBase(Branch branch, Branch otherBranch)
                             var second = forwardMerge.Parents.First();
                             Logger.WriteDebug("Second " + second.Sha);
                             var mergeBase = Repository.ObjectDatabase.FindMergeBase(commit, second);
-                            Logger.WriteDebug("New Merge base " + mergeBase.Sha);
-
+                            if (mergeBase == null)
+                            {
+                                Logger.WriteWarning("Could not find mergbase for " + commit);
+                            }
+                            else
+                            {
+                                Logger.WriteDebug("New Merge base " + mergeBase.Sha);
+                            }
                             if (mergeBase == findMergeBase)
                             {
                                 Logger.WriteDebug("Breaking");