mononoke/fastreplay: fix off-by-one in load tracking

Summary:
When max concurrency is 1, we should process at most one request concurrently,
not 2!  This had resulted in a flaky test since we're processing traffic out of
order there.

Reviewed By: HarveyHunt

Differential Revision: D19948594

fbshipit-source-id: 00268926095fdbbfdfd5a23366aafcfb763580f4

eden/mononoke/fastreplay/src/main.rs

@@ -388,7 +388,7 @@ async fn fastreplay<R: AsyncRead + Unpin>(
 
         let config = opts.config.get();
 
-        if load > config.max_concurrency()?.get() {
+        if load >= config.max_concurrency()?.get() {
             warn!(
                 &logger,
                 "Waiting for some requests to complete (load: {})...", load

eden/mononoke/tests/integration/test-fastreplay-inline-args.t

@@ -97,8 +97,8 @@ Check logging structure
   > EOF
   $ quiet fastreplay  --live-config "file:${live_config}" --debug --scuba-log-file "$fastreplay_log" < "$WIREPROTO_LOGGING_PATH"
   $ grep "Replay Succeeded" "$fastreplay_log" | jq .normal.command
-  "gettreepack"
   "getbundle"
+  "gettreepack"
   "getpackv1"
 
 # Check that replaying works with arguments