Jenkinsfile: Always build java sources if WORKSPACE file changed

Bug: Issue 11916
Change-Id: I0d273f8536c3b2ee10f8a6f938bc8dc3374ce0a5
diff --git a/Jenkinsfile b/Jenkinsfile
index 1b9e35f..ebf2136 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -139,7 +139,7 @@
     def polygerritFiles = changedFiles.findAll { it.startsWith("polygerrit-ui") ||
         it.startsWith("lib/js") }
 
-    if(polygerritFiles.size() > 0 || changedFiles.contains("WORKSPACE")) {
+    if(polygerritFiles.size() > 0) {
         if(changedFiles.size() == polygerritFiles.size()) {
             println "Only PolyGerrit UI changes detected, skipping other test modes..."
             Builds.modes = ["polygerrit"]
@@ -147,6 +147,9 @@
             println "PolyGerrit UI changes detected, adding 'polygerrit' validation..."
             Builds.modes += "polygerrit"
         }
+    } else if(changedFiles.contains("WORKSPACE")) {
+        println "WORKSPACE file changes detected, adding 'polygerrit' validation..."
+        Builds.modes += "polygerrit"
     }
 }