[Buglet] "git show <random-40-hexdigit>" gives an unclear error message

Here is one who wants to tackle potentially a low-hanging fruit.

  $ git cat-file -p 4cd96ce446ab653325a0e47fad73e94c99c57dd2
  error: unable to find 4cd96ce446ab653325a0e47fad73e94c99c57dd2
  fatal: Not a valid object name 4cd96ce446ab653325a0e47fad73e94c99c57dd2

This looks sensible and understandable, even though you could argue that
we don't have to say the same thing twice.  In the same repository:

  $ git show 4cd96ce446ab653325a0e47fad73e94c99c57dd3
  fatal: bad object 4cd96ce446ab653325a0e47fad73e94c99c57dd3

This is bad, as it sounds as if we found the named object but it is
corrupt.

[Sorry Junio, accidentally sent this to just you the first time around]

If "git show" is invoked on a hash for a file that doesn't exist, the
produced error message was "fatal: bad object <hash>". This is
misleading as the object isn't bad, but missing. As a matter of fact, if
an object is bad, this error message is never produced, because
parse_object() terminates with its own error message if the object is
corrupt.

This patch introduces a check to see whether an object exists (with the
appropriate error message if it doesn't) and removes the unnecessary and
misleading original error message if parse_object() fails.

Signed-off-by: Jakob Pfender <redacted>
---
  revision.c |    4 ++--
  1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/revision.c b/revision.c
index 86d2470..085aac2 100644
--- a/revision.c
+++ b/revision.c

@@ -173,9 +173,9 @@ static struct object *get_reference(struct rev_info 

*revs, const char *name, con
  {
      struct object *object;

+    if (sha1_object_info(sha1, NULL) < 0)
+        die("Not a valid object name %s", name);
      object = parse_object(sha1);
-    if (!object)
-        die("bad object %s", name);
      object->flags |= flags;
      return object;
  }
-- 
1.7.0.4