[526568] Switching to warning for dirty working tree.

[526568] Switching to warning for dirty working tree.
diff --git a/releng/org.eclipse.uml2.releng.tycho/pom.xml b/releng/org.eclipse.uml2.releng.tycho/pom.xml
index 1f3f23e..abd42a0 100644
--- a/releng/org.eclipse.uml2.releng.tycho/pom.xml
+++ b/releng/org.eclipse.uml2.releng.tycho/pom.xml
@@ -180,6 +180,7 @@
               pom.xml
               .polyglot.build.properties
             </jgit.ignore>
+            <jgit.dirtyWorkingTree>warning</jgit.dirtyWorkingTree>
           </configuration>
           <dependencies>
             <dependency>