port - python dependencies and github master

[CeDeROM]

Hello there :-)

I am writing a Makefile to a Python based port that gets the source
code from GitHub. Two questions:

1. How to change PORTVERSION / GH_COMMIT based on user choice /
option? One value for PORTVERSION seems fine but to change it to
master does not work..

2. Is the way to check python modules dependency correct?

PORTNAME=       cura
PORTVERSION=    14.06
#STABLEREL=     14.06
CATEGORIES=     cad

MAINTAINER=    blah at blah
COMMENT=        Cura is a complete and open slicing solution for
RepRap 3D printers.

OPTIONS_SINGLE= BTYPE
OPTIONS_SINGLE_BTYPE=   RELEASE DEVEL
OPTIONS_SUB=    yes
RELEASE_DESC=   Build latest stable release from github (${PORTVERSION})
DEVEL_DESC=     Build latest development snapshot from github master
OPTIONS_DEFAULT=        RELEASE

.include <bsd.port.options.mk>

#.if ${PORT_OPTIONS:MRELEASE}
#PORTVERSION=   ${STABLEREL}
#.endif

.if ${PORT_OPTIONS:MDEVEL}
PORTVERSION=    master
#STABLEREL=      master
.endif

#PORTVERSION=  ${STABLEREL}

USE_PYTHON=     yes
RUN_DEPENDS+=
${PYTHONPREFIX_SITELIBDIR}/OpenGL:${PORTSDIR}/graphics/py-opengl \
                ${PYTHONPREFIX_SITELIBDIR}/numpy:${PORTSDIR}/math/py-numpy \

${PYTHONPREFIX_SITELIBDIR}/setuptools:${PORTSDIR}/devel/py-setuptools
\
                ${PYTHONPREFIX_SITELIBDIR}/serial:${PORTSDIR}/comms/py-serial
BUILD_DEPENDS+= git:${PORTSDIR}/devel/git

USE_GITHUB=     yes
GH_ACCOUNT=     daid
GH_COMMIT=      ${PORTVERSION}

-- 
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info