LUCENE-9184, LUCENE-9183: allow skipping git status check in precommit with -Pvalidation.git.failOnModified=false (or place this in gradle.properties to make it permanent).

gradle/validation/git-status.gradle

@@ -15,8 +15,7 @@
  * limitations under the License.
  */
 
-// This adds top-level 'precommit' task with essential
+// This verifies local git repository's status.
-// precommit validation checks.
 
 import org.eclipse.jgit.api.*;
 import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
@@ -73,7 +72,17 @@ configure(rootProject) {
         }.sort()
 
         if (offenders) {
-          throw new GradleException("Working copy is not a clean git checkout, offending files:\n${offenders.join("\n")}")
+          def checkProp = "validation.git.failOnModified"
+          def shouldFail = Boolean.valueOf(propertyOrDefault(checkProp, true))
+          def message = "Working copy is not a clean git checkout" + 
+            (shouldFail ? " (skip with -P${checkProp}=false)" : "") +
+            ", offending files:\n${offenders.join("\n")}"
+
+          if (shouldFail) {
+            throw new GradleException(message)
+          } else {
+            logger.lifecycle("NOTE: ${message}")
+          }
         }
       }
     }