sha1-file: release strbuf after use

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1-file.c

@@ -799,6 +799,7 @@ static void read_alternate_refs(const char *path,
 
 	fclose(fh);
 	finish_command(&cmd);
+	strbuf_release(&line);
 }
 
 struct alternate_refs_data {