From 39f11bb10f8b0f8797110a6d8ce70b8c975e112f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Tue, 23 Nov 2021 20:38:07 +0100
Subject: Storage: reload head before update

---
 src/storage.cpp | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/storage.cpp b/src/storage.cpp
index f68cb68..05b100a 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -821,14 +821,15 @@ bool Storage::replaceHead(UUID type, UUID id, const Ref & old, const Ref & ref)
 
 optional<Ref> Storage::updateHead(UUID type, UUID id, const Ref & old, const std::function<Ref(const Ref &)> & f)
 {
-	Ref r = f(old);
-	if (r.digest() == old.digest() || replaceHead(type, id, old, r))
+	auto cur = old.storage().headRef(type, id);
+	if (!cur)
+		return nullopt;
+
+	Ref r = f(*cur);
+	if (r.digest() == cur->digest() || replaceHead(type, id, *cur, r))
 		return r;
 
-	if (auto cur = old.storage().headRef(type, id))
-		return updateHead(type, id, *cur, f);
-	else
-		return nullopt;
+	return updateHead(type, id, *cur, f);
 }
 
 int Storage::watchHead(UUID type, UUID wid, const std::function<void(const Ref &)> watcher) const
-- 
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