LordGrimmauld

buildscript {
    repositories {
        maven { url = 'https://files.minecraftforge.net/maven' }
        jcenter()
        mavenCentral()
        maven { url='https://repo.spongepowered.org/repository/maven-public/' }
    }
    dependencies {
        classpath group: 'net.minecraftforge.gradle', name: 'ForgeGradle', version: '3.+', changing: true
        classpath group: 'org.spongepowered', name: 'mixingradle', version: '0.7-SNAPSHOT'

LordGrimmauld

import org.gradle.nativeplatform.platform.internal.DefaultNativePlatform

def getGitHash = { ->
    def stdout = new ByteArrayOutputStream()
    exec {
        commandLine 'git', 'rev-parse', '--short', 'HEAD'
        standardOutput = stdout
    }
    return stdout.toString().trim()
}