t6300: test refs pointing to tree and blob

Adding tests for refs pointing to tree and blob shows that
we care about testing both positive ("see, my shiny new toy
does work") and negative ("and it won't do nonsensical
things when given an input it is not designed to work with")
cases.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index da59fad..e9f468d 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -650,6 +650,25 @@
 body contents
 $sig"
 
+test_expect_success 'set up refs pointing to tree and blob' '
+	git update-ref refs/mytrees/first refs/heads/master^{tree} &&
+	git update-ref refs/myblobs/first refs/heads/master:one
+'
+
+test_atom refs/mytrees/first subject ""
+test_atom refs/mytrees/first contents:subject ""
+test_atom refs/mytrees/first body ""
+test_atom refs/mytrees/first contents:body ""
+test_atom refs/mytrees/first contents:signature ""
+test_atom refs/mytrees/first contents ""
+
+test_atom refs/myblobs/first subject ""
+test_atom refs/myblobs/first contents:subject ""
+test_atom refs/myblobs/first body ""
+test_atom refs/myblobs/first contents:body ""
+test_atom refs/myblobs/first contents:signature ""
+test_atom refs/myblobs/first contents ""
+
 test_expect_success 'set up multiple-sort tags' '
 	for when in 100000 200000
 	do