t1409: let sed open its own input file

In one case, we were using a redirection operator to feed input into
sed. However, since sed is capable of opening its own input file, make
sed do that instead of redirecting input into it.

Signed-off-by: Denton Liu <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Denton-L

t/t1409-avoid-packing-refs.sh

@@ -8,7 +8,7 @@ test_description='avoid rewriting packed-refs unnecessarily'
 # shouldn't upset readers, and it should be omitted if the file is
 # ever rewritten.
 mark_packed_refs () {
-	sed -e "s/^\(#.*\)/\1 t1409 /" <.git/packed-refs >.git/packed-refs.new &&
+	sed -e "s/^\(#.*\)/\1 t1409 /" .git/packed-refs >.git/packed-refs.new &&
 	mv .git/packed-refs.new .git/packed-refs
 }