Bug 541741: [Releng] Enable error on dirtyWorkingTree

Change-Id: Iad134204b0139d11f4944dddba37d7ba31ccabfe
diff --git a/releng/pom.xml b/releng/pom.xml
index dbac77b..1202cc2 100644
--- a/releng/pom.xml
+++ b/releng/pom.xml
@@ -43,7 +43,7 @@
 		<maven.compiler.target>1.8</maven.compiler.target>
 		
 		<!-- if working tree is dirty (error|warning|ignore) -->
-		<dirtyWorkingTree>ignore</dirtyWorkingTree>
+		<dirtyWorkingTree>error</dirtyWorkingTree>
 		
 		<qualifier.format>yyyyMMddHHmm</qualifier.format>
 		<maven.build.timestamp.format>yyyyMMddHHmm</maven.build.timestamp.format>
@@ -192,6 +192,7 @@
 					
 					<jgit.ignore>
 						pom.xml
+						.polyglot.build.properties
 					</jgit.ignore>
 					<jgit.dirtyWorkingTree>${dirtyWorkingTree}</jgit.dirtyWorkingTree>