Skip commits that have no changes in path-limited +log

When I303d887ef8fbcfa1d3b5e60ba155ffb82b4f2c66 removed
FollowFilter it forgot to add an AndTreeFilter against ANY_DIFF
to replace it.

Bug: 35
Change-Id: Ia346363cd5594cf1563343a76de023f1743f84a8

gitiles-servlet/src/main/java/com/google/gitiles/LogServlet.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/LogServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/LogServlet.java
index 53cb426..ffad8d8 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/LogServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/LogServlet.java
@@ -42,7 +42,9 @@
 import org.eclipse.jgit.revwalk.RevObject;
 import org.eclipse.jgit.revwalk.RevTag;
 import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.treewalk.filter.AndTreeFilter;
 import org.eclipse.jgit.treewalk.filter.PathFilter;
+import org.eclipse.jgit.treewalk.filter.TreeFilter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -190,7 +192,9 @@
       walk.markUninteresting(walk.parseCommit(view.getOldRevision().getId()));
     }
     if (!Strings.isNullOrEmpty(view.getPathPart())) {
-      walk.setTreeFilter(PathFilter.create(view.getPathPart()));
+      walk.setTreeFilter(AndTreeFilter.create(
+          PathFilter.create(view.getPathPart()),
+          TreeFilter.ANY_DIFF));
     }
     return walk;
   }