Currently, a system property set via ‘gradle.properties’ wins over one passed with ‘-D’. Doesn’t seem right to me, but might be an intentional compromise because the other way around is difficult to implement. We are currently working on related stuff, so maybe we can do something about it. I’ve created GRADLE-2122 to track this.
Oops, I misread the part about system properties. Usually I overwrite props from gradle.properties with -P but I don’t know if this works if it is a system property. Apparently not