[evolution-data-server] Harden WebDAV contact backend by checking for etag being NULL

[Tobias Mueller <tobiasmue src gnome org>]

commit 7decaa3d48d3e7ea0010c946e299560c21d6fb1c
Author: Tobias Mueller <tobiasmue gnome org>
Date:   Mon Jun 1 01:10:03 2009 +0200

    Harden WebDAV contact backend by checking for etag being NULL
    
    Fixes bug 559980.
---
 .../backends/webdav/e-book-backend-webdav.c        |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/addressbook/backends/webdav/e-book-backend-webdav.c b/addressbook/backends/webdav/e-book-backend-webdav.c
index 7c087c9..c6aaef5 100644
--- a/addressbook/backends/webdav/e-book-backend-webdav.c
+++ b/addressbook/backends/webdav/e-book-backend-webdav.c
@@ -720,7 +720,7 @@ download_contacts(EBookBackendWebdav *webdav, EFlag *running,
 
 		contact = e_book_backend_cache_get_contact(priv->cache, complete_uri);
 		/* download contact if it is not cached or its ETag changed */
-		if (contact == NULL ||
+		if (contact == NULL || etag == NULL ||
 				strcmp(e_contact_get_const(contact, E_CONTACT_REV),etag) != 0) {
 			contact = download_contact(webdav, complete_uri);
 			if (contact != NULL) {