Remove Grgit/jgit usage in build.gradle

The replacement is objectively worse. However, it supports Git
worktrees, which sadly jgit does not.

We really need to rewrite the build script to make it lazy so we're not
executing these commands every time.

build.gradle

@@ -11,7 +11,6 @@ buildscript {
         classpath 'com.google.code.gson:gson:2.8.1'
         classpath 'net.minecraftforge.gradle:ForgeGradle:3.0.190'
         classpath 'net.sf.proguard:proguard-gradle:6.1.0beta2'
-        classpath 'org.ajoberstar.grgit:grgit-gradle:3.0.0'
     }
 }
 
@@ -25,7 +24,6 @@ plugins {
 }
 
 apply plugin: 'net.minecraftforge.gradle'
-apply plugin: 'org.ajoberstar.grgit'
 apply plugin: 'maven-publish'
 apply plugin: 'maven'
 
@@ -200,7 +198,6 @@ import com.google.gson.GsonBuilder
 import com.google.gson.JsonElement
 import com.hierynomus.gradle.license.tasks.LicenseCheck
 import com.hierynomus.gradle.license.tasks.LicenseFormat
-import org.ajoberstar.grgit.Grgit
 import proguard.gradle.ProGuardTask
 
 task proguard(type: ProGuardTask, dependsOn: jar) {
@@ -253,16 +250,15 @@ processResources {
     def hash = 'none'
     Set<String> contributors = []
     try {
-        def grgit = Grgit.open(dir: '.')
-        hash = grgit.head().id
+        hash = ["git", "-C", projectDir, "rev-parse", "HEAD"].execute().text.trim()
 
         def blacklist = ['GitHub', 'dan200', 'Daniel Ratcliffe']
-        grgit.log().each {
-            if (!blacklist.contains(it.author.name)) contributors.add(it.author.name)
-            if (!blacklist.contains(it.committer.name)) contributors.add(it.committer.name)
+        ["git", "-C", projectDir, "log", "--format=tformat:%an%n%cn"].execute().text.split('\n').each {
+            if (!blacklist.contains(it)) contributors.add(it)
         }
-    } catch(Exception ignored) { }
-
+    } catch(Exception e) {
+        e.printStackTrace()
+    }
     inputs.property "commithash", hash
 
     from(sourceSets.main.resources.srcDirs) {
@@ -606,18 +602,23 @@ githubRelease {
     token project.hasProperty('githubApiKey') ? project.githubApiKey : ''
     owner 'SquidDev-CC'
     repo 'CC-Tweaked'
-    try {
-        targetCommitish = Grgit.open(dir: '.').branch.current().name
-    } catch(Exception ignored) { }
+    targetCommitish.set(project.provider({
+        try {
+            return ["git", "-C", projectDir, "rev-parse", "--abbrev-ref", "HEAD"].execute().text.trim()
+        } catch (Exception e) {
+            e.printStackTrace()
+        }
+        return "master"
+    }))
 
     tagName "v${mc_version}-${mod_version}"
     releaseName "[${mc_version}] ${mod_version}"
-    body {
+    body.set(project.provider({
         "## " + new File(projectDir, "src/main/resources/data/computercraft/lua/rom/help/whatsnew.txt")
             .readLines()
             .takeWhile { it != 'Type "help changelog" to see the full version history.' }
             .join("\n").trim()
-    }
+    }))
     prerelease false
 }