Can't use -s base for empty suffix

syncmonitor/environment.py

@@ -89,6 +89,9 @@ class Provider:
         self.cookie = SyncreplCookie(cookie)
         self.mode = mode
 
+        if self.scope == ldap0.SCOPE_BASE and not searchbase:
+            self.scope = ldap0.SCOPE_SUBTREE
+
         self.behind = Watchdog(30)
         self.behind.triggered.connect(self._no_progress)
 
@@ -108,7 +111,7 @@ class Provider:
         control = ldap0.controls.syncrepl.SyncRequestControl(
             cookie=self.cookie, mode=self.mode)
 
-        self.search = self.client.search(self.base, scope=self.scope,
+        self.search = self.client.search(self.base, scope=self.scope, filterstr="(|)",
                 req_ctrls=[control])
         self.observer = SyncreplObserver(self.search, self.cookie)