Fix channel API for when the appscale secret changes.

AppController/djinn.rb

@@ -5219,7 +5219,14 @@ def start_xmpp_for_app(app, port, app_language)
     uac = UserAppClient.new(@userappserver_public_ip, @@secret)
     xmpp_user = "#{app}@#{login_ip}"
     xmpp_pass = HelperFunctions.encrypt_password(xmpp_user, @@secret)
-    uac.commit_new_user(xmpp_user, xmpp_pass, "app")
+    result = uac.commit_new_user(xmpp_user, xmpp_pass, "app")
+    Djinn.log_debug("User creation returned: #{result}")
+    if result.include?('Error: user already exists')
+      # We need to update the password of the channel XMPP account for 
+      # authorization.
+      result = uac.change_password(xmpp_user, xmpp_pass)
+      Djinn.log_debug("Change password returned: #{result}")
+    end
 
     Djinn.log_debug("Created user [#{xmpp_user}] with password [#{@@secret}] and hashed password [#{xmpp_pass}]")
 

AppController/lib/user_app_client.rb

@@ -94,6 +94,7 @@ def commit_new_user(user, encrypted_password, user_type, retry_on_except=true)
     else
       puts "\n[unexpected] Commit new user returned: [#{result}]"
     end
+    return result
   end
 
   def commit_new_app(user, app_name, language, file_location)