remote.c: remove BUG in show_push_unqualified_ref_name_error()

When "git push <remote> <src>:<dst>" does not spell out the
destination side of the ref fully, and when <src> is not given
as a reference but an object name, the code tries to give advice
messages based on the type of that object.

The type is determined by calling odb_read_object_info() and
signalled by its return value.  The code however reported a
programming error with BUG() when this function said that there
is no such object, which happens when the object name is given
as a full hexadecimal (if the object name is given as a partial
hexadecimal or an non-existing ref, the function would have died
without returning, so this BUG() wouldn't have triggered).  This
is wrong.  It is an ordinary end-user mistake to give an object
name that does not exist and treated as such.

An example of the error message produced is as follows:

	error: The destination you provided is not a full refname (i.e.,
	starting with "refs/"). We tried to guess what you meant by:

	- Looking for a ref that matches 'branch' on the remote side.
	- Checking if the <src> being pushed ('0000000000000000000000000000000000000001')
	  is a ref in "refs/{heads,tags}/". If so we add a corresponding
	  refs/{heads,tags}/ prefix on the remote side.

	Neither worked, so we gave up. You must fully qualify the ref.
	BUG: remote.c:1221: '0000000000000000000000000000000000000001' should be commit/tag/tree/blob, is '-1'
	fatal: the remote end hung up unexpectedly
	Aborted (core dumped)

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Denton-L

remote.c

@@ -1204,8 +1204,9 @@ static void show_push_unqualified_ref_name_error(const char *dst_value,
 			 "'%s:refs/tags/%s'?"),
 		       matched_src_name, dst_value);
 	} else {
-		BUG("'%s' should be commit/tag/tree/blob, is '%d'",
-		    matched_src_name, type);
+		advise(_("The <src> part of the refspec ('%s') "
+			 "is an object ID that doesn't exist.\n"),
+		       matched_src_name);
 	}
 }
 

t/t5516-fetch-push.sh

@@ -471,6 +471,11 @@ test_expect_success 'push ref expression with non-existent, incomplete dest' '
 	test_must_fail git push testrepo main^:branch
 '
 
+test_expect_success 'push ref expression with non-existent oid src' '
+	mk_test testrepo &&
+	test_must_fail git push testrepo $(test_oid 001):branch
+'
+
 for head in HEAD @
 do