Support relative paths in git.root

Author: sghill

src/integTest/groovy/nebula/plugin/release/ReleasePluginIntegrationSpec.groovy

@@ -23,10 +23,13 @@ import org.ajoberstar.grgit.Tag
 import org.gradle.api.plugins.JavaPlugin
 import org.gradle.internal.impldep.com.amazonaws.util.Throwables
 import org.gradle.testkit.runner.BuildResult
+import org.gradle.testkit.runner.GradleRunner
 import org.gradle.testkit.runner.TaskOutcome
 import spock.lang.Ignore
 import spock.lang.Unroll
 
+import java.nio.file.Files
+
 class ReleasePluginIntegrationSpec extends GitVersioningIntegrationTestKitSpec {
     @Override
     def setupBuild() {
@@ -1281,6 +1284,26 @@ nebula.release.features.immutableSnapshot.timestampPrecision=${precision.name()}
         TimestampPrecision.MILLISECONDS |  17
     }
 
+    def 'can use relative git.root'() {
+        given:
+        def subdir = new File(projectDir, 'subdir')
+        subdir.mkdirs()
+        ['build.gradle', 'settings.gradle'].each {
+            def file = new File(projectDir, it)
+            Files.move(file.toPath(), new File(subdir, it).toPath())
+        }
+        new File(subdir, 'gradle.properties') << 'git.root=..'
+
+        when:
+        def result = GradleRunner.create()
+                .withProjectDir(subdir)
+                .withArguments('help', '-s')
+                .withPluginClasspath()
+                .build()
+
+        then:
+        result.task(':help').outcome == TaskOutcome.SUCCESS
+    }
 
 
     private void replaceDevWithImmutableSnapshot() {

src/main/groovy/nebula/plugin/release/ReleasePlugin.groovy

@@ -57,7 +57,7 @@ class ReleasePlugin implements Plugin<Project> {
     @CompileDynamic
     @Inject
     ReleasePlugin(Project project, ExecOperations execOperations, ProviderFactory providerFactory) {
-        this.gitRoot = project.hasProperty('git.root') ? new File(project.property('git.root')) : project.rootProject.projectDir
+        this.gitRoot = project.hasProperty('git.root') ? project.file(project.property('git.root')) : project.rootProject.projectDir
         this.gitBuildService = project.getGradle().getSharedServices().registerIfAbsent("gitBuildService", GitBuildService.class, spec -> {
             spec.getParameters().getGitRootDir().set(gitRoot)
         }).get()

src/main/groovy/nebula/plugin/release/git/base/BaseReleasePlugin.groovy

@@ -41,7 +41,7 @@ class BaseReleasePlugin implements Plugin<Project> {
 
     void apply(Project project) {
         ReleasePluginExtension releasePluginExtension = project.extensions.create('release', ReleasePluginExtension, project)
-        File gitRoot = project.hasProperty('git.root') ? new File(project.property('git.root')) : project.rootProject.projectDir
+        File gitRoot = project.hasProperty('git.root') ? project.file(project.property('git.root')) : project.rootProject.projectDir
         this.gitBuildService = project.getGradle().getSharedServices().registerIfAbsent("gitBuildService", GitBuildService.class, spec -> {
             spec.getParameters().getGitRootDir().set(gitRoot)
         })

src/main/groovy/nebula/plugin/release/git/base/ReleasePluginExtension.groovy

@@ -67,7 +67,7 @@ class ReleasePluginExtension {
     @CompileDynamic
     @Inject
     ReleasePluginExtension(Project project) {
-        File gitRoot = project.hasProperty('git.root') ? new File(project.property('git.root')) : project.rootProject.projectDir
+        File gitRoot = project.hasProperty('git.root') ? project.file(project.property('git.root')) : project.rootProject.projectDir
         this.project = project
         this.gitBuildService = project.getGradle().getSharedServices().registerIfAbsent("gitBuildService", GitBuildService.class, spec -> {
             spec.getParameters().getGitRootDir().set(gitRoot)