lib: Delete the entire access-list only if there are no more entries

When you enter the access-list with the same sequence number but with a
different prefix AND access-list has only a single entry, then the entry
is deleted and the whole access-list is deleted.

That means that "replace entry" never be re-inserted.

With fix:
```
~# vtysh -c 'c' -c 'access-list 1 seq 10 permit 127.0.0.10/32'
~# vtysh -c 'sh run' | grep access-list
access-list 1 seq 10 permit 127.0.0.10/32
~# vtysh -c 'c' -c 'access-list 1 seq 10 permit 127.0.0.20/32'
~# vtysh -c 'sh run' | grep access-list
access-list 1 seq 10 permit 127.0.0.20/32
~# vtysh -c 'c' -c 'access-list 1 seq 11 permit 127.0.0.11/32'
~# vtysh -c 'sh run' | grep access-list
access-list 1 seq 10 permit 127.0.0.20/32
access-list 1 seq 11 permit 127.0.0.11/32
~# vtysh -c 'c' -c 'no access-list 1 seq 10 permit 127.0.0.20/32'
~# vtysh -c 'sh run' | grep access-list
access-list 1 seq 11 permit 127.0.0.11/32
~#
```

Signed-off-by: Donatas Abraitis <donatas.abraitis@gmail.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/filter.c b/lib/filter.c
index 17ca4689f4..4a83b8b043 100644
--- a/lib/filter.c
+++ b/lib/filter.c
@@ -451,6 +451,7 @@ static void access_list_filter_delete(struct access_list *access,
 				      struct filter *filter)
 {
 	struct access_master *master;
+	struct filter *replace = filter;
 
 	master = access->master;
 
@@ -472,7 +473,7 @@ static void access_list_filter_delete(struct access_list *access,
 		(*master->delete_hook)(access);
 
 	/* If access_list becomes empty delete it from access_master. */
-	if (access_list_empty(access))
+	if (access_list_empty(access) && !replace)
 		access_list_delete(access);
 }