manifest: increase lrucache from 3 to 4...
manifest: increase lrucache from 3 to 4
During a commit amend there are 4 manifests being handled:
- original commit
- temporary commit
- amended commit
- merge base
This causes a manifest cache miss which hurts perf on large repos. On a large
repo, this fix causes amend to go from 6 seconds to 5.5 seconds.