On poudriere jail (Poudriere version: 3.3.2, Host OSVERSION: 1300020, Jail OSVERSION: 1300020) running on CURRENT host (FreeBSD 13.0-CURRENT #3 r346431: Sat Apr 20 10:02:02 CEST 2019 amd64) building of sysutils/bareos-client fails when option PYTHON is enabled; see error below.

[...]
=>> Building sysutils/bareos-client
build started at Mon Apr 22 02:58:30 UTC 2019
port directory: /usr/ports/sysutils/bareos-client
package name: bareos-client-17.2.7_2
building for: FreeBSD xxx.xxx  13.0-CURRENT FreeBSD 13.0-CURRENT 1300020 amd64
maintained by: acm@FreeBSD.org
Makefile ident:      $FreeBSD: head/sysutils/bareos-client/Makefile 485488 2018-11-20 21:48:50Z acm $
Poudriere version: 3.3.2
Host OSVERSION: 1300020
Jail OSVERSION: 1300020
Job Id: 02

[...]
---Begin OPTIONS List---
===> The following configuration options are available for bareos-client-17.2.7_2:
     LMDB=off: Enable build of LMDB support
     NLS=on: Native Language Support
     PYTHON=on: Python bindings or support
     SCSICRYPTO=on: Build LTO AME crypto plugin
====> Cryptographic library: you have to select exactly one of them
     OPENSSL=on: SSL/TLS support via OpenSSL
     GNUTLS=off: SSL/TLS support via GnuTLS
===> Use 'make config' to modify these settings
---End OPTIONS List---
[...]

The error shows up as:

[...]
checking for cmocka.h... no
no
checking for Python support... no
configure: error: Unable to find Python.h in standard locations
===>  Script "configure" failed unexpectedly.
Please report the problem to acm@FreeBSD.org [maintainer] and attach the
"/wrkdirs/usr/ports/sysutils/bareos-client/work/bareos-Release-17.2.7/config.log"
including the output of the failure of your make command. Also, it might be
a good idea to provide an overview of all packages installed on your system
(e.g. a /usr/local/sbin/pkg-static info -g -Ea).
*** Error code 1