Fix deleting reflog entries from HEAD reflog

dwim_ref() used to resolve HEAD symbolic ref to its target (i.e. current
branch).  This incorrectly removed the reflog entry from the current
branch when 'git reflog delete HEAD@{1}' was asked for.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin-reflog.c b/builtin-reflog.c
index 125d455..7d7047d 100644
--- a/builtin-reflog.c
+++ b/builtin-reflog.c
@@ -604,8 +604,8 @@
 			continue;
 		}
 
-		if (!dwim_ref(argv[i], spec - argv[i], sha1, &ref)) {
-			status |= error("%s points nowhere!", argv[i]);
+		if (!dwim_log(argv[i], spec - argv[i], sha1, &ref)) {
+			status |= error("no reflog for '%s'", argv[i]);
 			continue;
 		}