QPID-6109: don't require password to be specified to allow PLAIN
diff --git a/qpid/sasl.py b/qpid/sasl.py
index 25de6de..85e31e3 100644
--- a/qpid/sasl.py
+++ b/qpid/sasl.py
@@ -88,7 +88,7 @@
 
   def start(self, mechanisms):
     mechs = mechanisms.split()
-    if self.attrs.get("username") and self.attrs.get("password") and "PLAIN" in mechs:
+    if self.attrs.get("username") and "PLAIN" in mechs:
       return "PLAIN", "\0%s\0%s" % (self.attrs.get("username"), self.attrs.get("password"))
     elif "ANONYMOUS" in mechs:
       return "ANONYMOUS", "%s@%s" % (self.attrs.get("username"), socket.gethostname())