SMBD User authentication doesn't work after dist upgrade to 15.10

After upgrading to 15.10 my samba share stopped working. Guest shares work, but user authentication does not. After browsing to the share the user and password prompt is displayed but fails even with the correct credentials.

I tried purging the samba packages and rewriting the configuration from a clean copy of /etc/samba/smb.conf
The user is present in smbpasswd.
The share configuration is of the form:

[myshare]
   guest ok = no
   path = /home/username/myshare
   browseable = yes
   read only = no
   valid users = username
   user = username

As a workaround I created a linux container for ubuntu 15.04, installed samba, used the same configuration, created the user, mounted the users home directory using --bind, and forwarded ports 139, and 445 and was able to get it to work.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: samba 2:4.1.17+dfsg-4ubuntu2
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu3
Architecture: amd64
BothFailedConnect: Yes
Date: Fri Oct 23 12:35:26 2015
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SambaServerRegression: Yes
SmbConfIncluded: No
SourcePackage: samba
UpgradeStatus: Upgraded to wily on 2015-10-22 (1 days ago)
upstart.smbd.override: manual