Fix joining rooms through aliases where the alias server isn't a real homeserver (#15776)

2 files changed, 2 insertions, 1 deletions

diff --git a/changelog.d/15776.bugfix b/changelog.d/15776.bugfix
new file mode 100644

index 0000000000..f146a85f1a
--- /dev/null
+++ b/changelog.d/15776.bugfix
@@ -0,0 +1 @@
+Fix joining rooms through aliases where the alias server isn't a real homeserver. Contributed by @tulir @ Beeper.
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py

index af0ca5c26d..55df34bd06 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -1498,7 +1498,7 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
         # put the server which owns the alias at the front of the server list.
         if room_alias.domain in servers:
             servers.remove(room_alias.domain)
-        servers.insert(0, room_alias.domain)
+            servers.insert(0, room_alias.domain)
 
         return RoomID.from_string(room_id), servers