NoMethodError: undefined method `commits_count' for nil:NilClass
https://sentry.gitlab.net/gitlab/gitlabcom/issues/779729/
NoMethodError: undefined method `commits_count' for nil:NilClass
merge_request.rb:355:in `commits_count'
merge_request_diff.commits_count
gitlab/metrics/instrumentation.rb:161:in `block in commits_count'
.measure { super }
gitlab/metrics/method_call.rb:36:in `measure'
retval = yield
gitlab/metrics/instrumentation.rb:161:in `commits_count'
.measure { super }
projects/merge_requests_controller.rb:47:in `block (2 levels) in show'
@commits_count = @merge_request.commits_count
...
(122 additional frame(s) were not displayed)
NoMethodError: undefined method `commits_count' for nil:NilClass