Ignore sentinel values in About computation.

Review by: fabbott (desk)

git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/1.6@4432 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/dev/core/src/com/google/gwt/dev/About.java b/dev/core/src/com/google/gwt/dev/About.java
index b64eb5a..e6dabfb 100644
--- a/dev/core/src/com/google/gwt/dev/About.java
+++ b/dev/core/src/com/google/gwt/dev/About.java
@@ -42,11 +42,14 @@
     }
 
     GWT_SVNREV = props.getProperty("gwt.svnrev");
-    if (GWT_SVNREV == null) {
+    // Check for null or sentinel value (break up to avoid text replace)
+    if (GWT_SVNREV == null || GWT_SVNREV.equals("@GWT_" + "SVNREV@")) {
       GWT_SVNREV = "unknown";
     }
+
     GWT_VERSION_NUM = props.getProperty("gwt.version");
-    if (GWT_VERSION_NUM == null) {
+    // Check for null or sentinel value (break up to avoid text replace)
+    if (GWT_VERSION_NUM == null || GWT_VERSION_NUM.equals("@GWT_" + "VERSION@")) {
       GWT_VERSION_NUM = "0.0.0";
     }
     GWT_VERSION = GWT_NAME + " " + GWT_VERSION_NUM;