LogServlet: use RevSort.TOPO_KEEP_BRANCH_TOGETHER

For the "topo-order" parameter in +log, use
RevSort.TOPO_KEEP_BRANCH_TOGETHER instead of RevSort.TOPO. Using
RevSort.TOPO_KEEP_BRANCH_TOGETHER causes JGit RevWalk to return commits
in topological order without intermixing lines of commit history. This
behavior is more similar than the behavior of RevSort.TOPO to using
"git log --topo-order" because RevSort.TOPO does not guarantee that
lines of history are not intermixed.

Signed-off-by: Alex Spradlin <alexaspradlin@google.com>
Change-Id: Ic59bfb8e1526615b261c0fac0b57aad107e3fa7d

java/com/google/gitiles/LogServlet.java

diff --git a/java/com/google/gitiles/LogServlet.java b/java/com/google/gitiles/LogServlet.java
index c738f0e..645264b 100644
--- a/java/com/google/gitiles/LogServlet.java
+++ b/java/com/google/gitiles/LogServlet.java
@@ -230,7 +230,7 @@
       walk.setFirstParent(true);
     }
     if (isTrue(view, TOPO_ORDER_PARAM)) {
-      walk.sort(RevSort.TOPO, true);
+      walk.sort(RevSort.TOPO_KEEP_BRANCH_TOGETHER, true);
     }
     if (isTrue(view, REVERSE_PARAM)) {
       walk.sort(RevSort.REVERSE, true);

javatests/com/google/gitiles/LogServletTest.java

diff --git a/javatests/com/google/gitiles/LogServletTest.java b/javatests/com/google/gitiles/LogServletTest.java
index 7232439..4ef7a4d 100644
--- a/javatests/com/google/gitiles/LogServletTest.java
+++ b/javatests/com/google/gitiles/LogServletTest.java
@@ -80,6 +80,24 @@
   }
 
   @Test
+  public void topoKeepBranchTogetherLog() throws Exception {
+    RevCommit a = repo.update("master", repo.commit().add("foo", "foo\n"));
+    RevCommit b1 = repo.update("master", repo.commit().parent(a).add("foo", "foo3\n"));
+    RevCommit c = repo.update("master", repo.commit().parent(a).add("foo", "foo2\n"));
+    RevCommit b2 = repo.update("master", repo.commit().parent(b1).add("foo", "foo4\n"));
+    RevCommit d = repo.update("master", repo.commit().parent(c).parent(b2).add("foo", "foo5\n"));
+
+    Log response = buildJson(LOG, "/repo/+log/master", "topo-order");
+    assertThat(response.log).hasSize(5);
+
+    verifyJsonCommit(response.log.get(0), d);
+    verifyJsonCommit(response.log.get(1), b2);
+    verifyJsonCommit(response.log.get(2), b1);
+    verifyJsonCommit(response.log.get(3), c);
+    verifyJsonCommit(response.log.get(4), a);
+  }
+
+  @Test
   public void follow() throws Exception {
     String contents = "contents";
     RevCommit c1 = repo.branch("master").commit().add("foo", contents).create();