Deprecated regex statement on install.

[RyoshiKayo]

Installed postgresql via "sudo apt install postgresql" and saw the following message:

Removing obsolete dictionary files:
Setting up postgresql-9.5 (9.5.10-0ubuntu0.16.04) ...
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/(?<!\\)\${ <-- HERE ([^}]+)}/ at /usr/sbin/pam_getenv line 78.

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Codename: xenial

$ apt-cache policy postgresql
postgresql:
  Installed: 9.5+173ubuntu0.1
  Candidate: 9.5+173ubuntu0.1
  Version table:
 *** 9.5+173ubuntu0.1 500
        500 http://ubuntu.mirrors.ovh.net/ubuntu xenial-updates/main amd64 Packages
        500 http://ubuntu.mirrors.ovh.net/ubuntu xenial-updates/main i386 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu xenial-security/main i386 Packages
        100 /var/lib/dpkg/status
     9.5+173 500
        500 http://ubuntu.mirrors.ovh.net/ubuntu xenial/main amd64 Packages
        500 http://ubuntu.mirrors.ovh.net/ubuntu xenial/main i386 Packages