Provide nicer toString if destBranch is "*".

Change-Id: I68f20f70acdc581a9c0c3a99bba6b692b6a6447c

src/main/java/com/googlesource/gerrit/plugins/supermanifest/SuperManifestRefUpdatedListener.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/supermanifest/SuperManifestRefUpdatedListener.java b/src/main/java/com/googlesource/gerrit/plugins/supermanifest/SuperManifestRefUpdatedListener.java
index 476f244..9672b6d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/supermanifest/SuperManifestRefUpdatedListener.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/supermanifest/SuperManifestRefUpdatedListener.java
@@ -122,7 +122,11 @@
     String destBranch;
 
     public String src() {
-      return srcRepoKey + ":" + srcRef + ":" + xmlPath;
+      String src = srcRef;
+      if (destBranch.equals("*")) {
+        src = "*";
+      }
+      return srcRepoKey + ":" + src + ":" + xmlPath;
     }
 
     public String dest() {