#64 xrdp error on space in AD username

[Viewpoint Zero]

I have installed xrdp (0.6.1-2) on Ubuntu 16.04 LTS with Mate Desktop Environment.
All installs from default repositories, no custom compiles, no custom repositories.

The logins for Ubuntu local users work fine -- I can login and use windowed environment from both Windows 10 using mstsc RDP as well as from thin clients (HP t520).

However, I also have Active Directory integration with winbind/samba, which (unfortunately) has domain logins in form "firstname lastname".

These logins work from SSH, I can login with domain user and use Ubuntu normally.

However, when trying to access Ubuntu via xrdp (sessman-Xvnc), I get login error messages in logfile, as it seems xrdp doesn't quote space in usernames and therefore doesn't pass username correctly to xhost:

Here are the log entries from login attempts when entering "firstname lastname" in login box:

xhost:  bad hostname "lastname"
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  109 (X_ChangeHosts)
  Value in failed request:  0x5
  Serial number of failed request:  6
  Current serial number in output stream:  8
localuser:firstname being added to access control list
xhost:  bad hostname "lastname"
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  109 (X_ChangeHosts)
  Value in failed request:  0x5
  Serial number of failed request:  6
  Current serial number in output stream:  8
openConnection: connect: No such file or directory
cannot connect to brltty at :0
/etc/xrdp/startwm.sh: 3: [: x: unexpected operator
/bin/bash: /home/DOMAIN/firstname: No such file or directory

(Btw, quoting the username with " or ' , or adding a backslash before space doesn't work either)