issues mapping libpurple xmpp to matrix

Nobody has claimed this yet.

Let's assume that I have added purple xmpp account with JID pvagner@puppeting.xmpp .
I have used
```
accounts map-existing xmpp pvagner@puppeting.xmpp
```
Thus it should be correctly mapped to my matrix account for future bridging.

When I receive a new XMPP message on said account, the bridge prints this into the log:
```
(18:51:37) jabber: Recv (ssl)(228):
(18:51:39) jabber: Recv (ssl)(245): error 1
(18:51:39) prefs: purple_prefs_get_bool: Unknown pref /purple/logging/log_ims
(18:51:39) jabber: Recv (ssl)(225):
Jan-2 18:51:39.575 ERROR Store Could not find an account for prpl-jabber://pvagner@puppeting.xmpp/. Either the accountis not assigned to a matrix user, or we have hit a bug.
```

I can partially workaround this by adding slash to the end of my JID inside the file user-store.db manually however I'm afraid it might break something else.

Reproduce the mapping with `accounts map-existing xmpp pvagner@puppeting.xmpp` and inspect the Store lookup reported in the log, along with the corresponding entry in `user-store.db`. Done means an incoming XMPP message resolves the mapped Matrix account without manually changing the stored JID.

Written by the indexing model from the issue text.