add fail statements for better diagnostics

releng.wtpbuilder/distribution/xsl.site/publish.xml

@@ -12,7 +12,12 @@
 
     <property environment="env" />
 
-    <property
+	 <fail unless="buildDirectory" message="buildDirectory must be provided to publish" />
+   <fail unless="buildLabel"     message="buildLabel must be provided to publish" />
+	 <fail unless="wtp.builder.home" message="wtp.builder.home must be provided to publish" />
+   <fail unless="build.distribution" message="build.distribution must be provided to publish" />
+
+	<property
         name="resultDir"
         value="${buildDirectory}/${buildLabel}" />
 	<!--name of generated index page-->