Merge branch 'dt/cat-file-batch-ambiguous'

"git cat-file --batch" reported a dangling symbolic link by
mistake, when it wanted to report that a given name is ambiguous.

* dt/cat-file-batch-ambiguous:
  t1512: test ambiguous cat-file --batch and --batch-output
  Do not print 'dangling' for cat-file in case of ambiguity

diff --cc Documentation/git-cat-file.txt
Simple merge

diff --cc cache.h
Simple merge

diff --cc tree-walk.c
Simple merge

diff --cc tree-walk.h
Simple merge