[evolution-data-server] Fix a crash under e_webdav_discover_traverse_propfind_response_cb()

[Milan Crha <mcrha src gnome org>]

commit af997bc141094aec86752d567231d914b8b0602c
Author: Milan Crha <mcrha redhat com>
Date:   Fri Jun 9 11:59:24 2017 +0200

    Fix a crash under e_webdav_discover_traverse_propfind_response_cb()
    
    In some cases, like when evolution-source-registry searches for ownCloud
    sources, the out_calendar_user_addresses could be NULL, but the crashing
    function had been dereferencing it anyway.

 src/libedataserver/e-webdav-discover.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/src/libedataserver/e-webdav-discover.c b/src/libedataserver/e-webdav-discover.c
index 43eaeff..8621a5e 100644
--- a/src/libedataserver/e-webdav-discover.c
+++ b/src/libedataserver/e-webdav-discover.c
@@ -174,7 +174,10 @@ e_webdav_discover_traverse_propfind_response_cb (EWebDAVSession *webdav,
                if (xpath_obj) {
                        gint ii, length;
 
-                       length = xmlXPathNodeSetGetLength (xpath_obj->nodesetval);
+                       if (wdd->out_calendar_user_addresses)
+                               length = xmlXPathNodeSetGetLength (xpath_obj->nodesetval);
+                       else
+                               length = 0;
 
                        for (ii = 0; ii < length; ii++) {
                                gchar *address_href;