Sort the jar files from the war before adding to classpath.

Currently, the order they are inserted onto the classpath depends on
directory iteration order of the WEB-INF directory at war-file
building time. On some filesystems that is alphabetical, and on some
filesystems, it is completely arbitrary. On the second kind of
filesystem, gerrit-patch-jgit can randomly end up on the classpath
*after* jgit itself, thus causing it to not be loaded.

Change-Id: I4ee9b22cbb93405e033f6f6bda9da1dd87b3419f

gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java

@@ -31,6 +31,8 @@ import java.net.URL;
 import java.net.URLClassLoader;
 import java.security.CodeSource;
 import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.Enumeration;
 import java.util.jar.Attributes;
 import java.util.jar.JarFile;
@@ -235,6 +237,12 @@ public final class GerritLauncher {
     if (jars.isEmpty()) {
       return GerritLauncher.class.getClassLoader();
     }
+    Collections.sort(jars, new Comparator<URL>() {
+      public int compare(URL o1, URL o2) {
+        return o1.toString().compareTo(o2.toString());
+      }
+    });
+
     return new URLClassLoader(jars.toArray(new URL[jars.size()]));
   }