[PATCH] Fixing segmentation fault when merging FETCH_HEAD

["Jose Ivan B. Vilarouca Filho" <joseivan@lavid.ufpb.br>]

From: "Jose Ivan B. Vilarouca Filho" <joseivan@lavid.ufpb.br>

A segmentaion fault is raised when trying to merge FETCH_HEAD
formed only by "not-for-merge" refs.

Ex:
    git init .
    git remote add origin ...
    git fetch origin
    git merge FETCH_HEAD

Signed-off-by: Jose Ivan B. Vilarouca Filho <joseivan@lavid.ufpb.br>
---
 builtin/merge.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/builtin/merge.c b/builtin/merge.c
index 101ffef..7e419dc 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1270,9 +1270,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			    "an empty head"));
 		remoteheads = collect_parents(head_commit, &head_subsumed,
 					      argc, argv, NULL);
-		remote_head = remoteheads->item;
-		if (!remote_head)
+		if ((!remoteheads) || (!remoteheads->item))
 			die(_("%s - not something we can merge"), argv[0]);
+		remote_head = remoteheads->item;
 		if (remoteheads->next)
 			die(_("Can merge only exactly one commit into empty head"));
 		read_empty(remote_head->object.oid.hash, 0);
-- 
1.7.10.4