From 76508320025a2258ccf169de2f559ad01f27281b Mon Sep 17 00:00:00 2001
From: Matthias Sohn <matthias.sohn@sap.com>
Date: Tue, 4 Oct 2022 15:42:25 +0200
Subject: [PATCH] FetchCommand: fix fetchSubmodules to work on a Ref to a blob

FetchCommand#fetchSubmodules assumed that FETCH_HEAD can always be
parsed as a tree. This isn't true if it refers to a Ref referring to a
BLOB. This is e.g. used in Gerrit for Refs like refs/sequences/changes
which are used to implement sequences stored in git.

Change-Id: I414f5b7d9f2184b2d7d53af1dfcd68cccb725ca4
---
 org.eclipse.jgit/src/org/eclipse/jgit/api/FetchCommand.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/FetchCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/FetchCommand.java
index 90c1515b0..7290d83df 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/FetchCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/FetchCommand.java
@@ -140,6 +140,9 @@ private void fetchSubmodules(FetchResult results)
 			if (fetchHead == null) {
 				return;
 			}
+			if (revWalk.parseAny(fetchHead).getType() == Constants.OBJ_BLOB) {
+				return;
+			}
 			walk.setTree(revWalk.parseTree(fetchHead));
 			while (walk.next()) {
 				try (Repository submoduleRepo = walk.getRepository()) {