Remove unused commit field from SyncProjectRequest

Gerrit hasn't required the commit field per-branch in a long time,
since before the code tree was open sourced.  It was an accident
that we didn't remove this sooner, as it only complicates the
project initialization process.

Signed-off-by: Shawn O. Pearce <sop@google.com>

mgrapp/src/com/google/codereview/manager/ProjectSync.java

@@ -113,7 +113,6 @@ public class ProjectSync {
   private BranchSync toBranch(final Ref r, final RevCommit c) {
     final BranchSync.Builder bs = BranchSync.newBuilder();
     bs.setBranchName(r.getName());
-    bs.setCommit(GitMetaUtil.toGitCommit(c));
     return bs.build();
   }
 

proto/internal/sync_project.proto

@@ -15,11 +15,9 @@
 package codereview.internal;
 option java_package = "com.google.codereview.internal";
 
-import "git_meta.proto";
-
 message BranchSync {
   required string branch_name = 1;
-  required GitCommit commit = 2;
+  // field 2 used to be "commit"
 }
 
 message SyncProjectRequest {