[PATCH] parse_tag: fail, if tagged objected would be NULL

The cause of a NULL in tag->tagged can be:
* a unknown object type is used
* the tag points to a object with an other type as stated
  in the tag.

Both situations are most likley be caused by a not welformed
tag. Catching this error here avoids doing tag->tagged!=NULL
checks in the rest of git.

Signed-off-by: Martin Koegler <redacted>
---
In my option, this change would simplity many things.

tag.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/tag.c b/tag.c
index 38bf913..96fef70 100644
--- a/tag.c
+++ b/tag.c

@@ -82,8 +82,12 @@ int parse_tag_buffer(struct tag *item, void *data, unsigned long size)
 	} else {
 		error("Unknown type %s", type);
 		item->tagged = NULL;
+		return -1;
 	}
 
+	if (!item->tagged)
+		return -1;
+
 	if (item->tagged && track_object_refs) {
 		struct object_refs *refs = alloc_object_refs(1);
 		refs->ref[0] = item->tagged;

-- 
1.5.4.1.gcb4c5