return only one url

needed for test=True where compare one URL with an array of URLs failed

salt/modules/zypper.py

@@ -378,7 +378,7 @@ class _RepoInfo(object):
 
     @property
     def url(self):
-        return [url.asCompleteString() for url in self.zypp.baseUrls()]
+        return self.zypp.url().asCompleteString()
 
     @url.setter
     def url(self, value):