Get short commit ref using a more proper method

patches/server/0001-Setup-Gradle-project.patch

@@ -20,7 +20,7 @@ index 67fb370cad6924895a6b27052dbd5c1767e3f0c9..3e05459f27c4c5697ae65da504d67a6a
  /.project
 diff --git a/build.gradle.kts b/build.gradle.kts
 new file mode 100644
-index 0000000000000000000000000000000000000000..9b738b8561f75a2531d64abb36f4cd9d9561cbfc
+index 0000000000000000000000000000000000000000..6e5431276a68204ab7aee451b2074afc371068b5
 --- /dev/null
 +++ b/build.gradle.kts
 @@ -0,0 +1,135 @@
@@ -70,7 +70,7 @@ index 0000000000000000000000000000000000000000..9b738b8561f75a2531d64abb36f4cd9d
 +
 +    manifest {
 +        val git = Git(rootProject.layout.projectDirectory.path)
-+        val gitHash = git("rev-parse", "HEAD").getText().substring(0, 7)
++        val gitHash = git("rev-parse", "--short=7", "HEAD").getText()
 +        val implementationVersion = System.getenv("BUILD_NUMBER") ?: "\"$gitHash\""
 +        attributes(
 +            "Main-Class" to "org.bukkit.craftbukkit.Main",