It appears that get_oid_with_context calls into get_short_oid for that
case, and get_short_oid returns SHORT_NAME_AMBIGUOUS, which is -2.  We
treat that as DANGLING_SYMLINK, which also seems to have the value -2. 
So, it's an ambiguity in ambiguity resolution.

Fix attached.  

On Fri, 2019-01-18 at 03:38 +0000, Eric Wong wrote:
> Hi David,
> 
> Perhaps I'm confused, the cat-file manpage seems to indicate
> "dangling" only gets printed if I use "--follow-symlinks".
> 
> However, I'm not using "--follow-symlinks" and I get
> "dangling" when passing ambiguous object IDs:
> 
> Trying to check the ambiguous "dead" against git.git, I get:
> 
> 	$ echo dead | git cat-file --batch-check 2>/dev/null
> 	dangling 4
> 	dead
> 
> Is the above intended?
> 
> stderr shows the ambiguity and gives me hints, which is expected.
> 
> Thanks.
>