From 2d07c73777e837213f1c3c85b9cb446aac8b6170 Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
Date: Mon, 13 Jan 2020 12:47:30 +0000
Subject: [PATCH] Don't assign numeric IDs for empty usernames (#6690)

Fix a bug where we would assign a numeric userid if somebody tried registering
with an empty username
---
 changelog.d/6690.bugfix      | 1 +
 synapse/handlers/register.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/6690.bugfix

diff --git a/changelog.d/6690.bugfix b/changelog.d/6690.bugfix
new file mode 100644
index 000000000..30ce1dc9f
--- /dev/null
+++ b/changelog.d/6690.bugfix
@@ -0,0 +1 @@
+Fix a bug where we would assign a numeric userid if somebody tried registering with an empty username.
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 8a7d965fe..885da8298 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -174,7 +174,7 @@ class RegistrationHandler(BaseHandler):
         if password:
             password_hash = yield self._auth_handler.hash(password)
 
-        if localpart:
+        if localpart is not None:
             yield self.check_username(localpart, guest_access_token=guest_access_token)
 
             was_guest = guest_access_token is not None