Remove line auto-assigning a variable to nil

This is one of the most strange behaviours in ruby: if a variable
doesn't exist, assigning to itself will return `nil`.

So a line like:

mdmkdfm = ooops if mdmkdfm.respond_to?(:uiqpior)

Surprisingly will not raise any errors: the nonexistent `mdmkdfm`
variable will be evaluated to `nil`, `mdmkdfm.respond_to?(:uiqpior)`
will evaluate to `nil.respond_to?(:uiqpior)`, which will return `false`,
and then the line will be evaluated as `mdmkdfm = ooops if false`, which
will return `nil`.

Maybe in the future Ruby will change this behaviour. We hope CONSUL is
now in better shape if that ever happens :).

app/helpers/stats_helper.rb

@@ -25,7 +25,6 @@ module StatsHelper
   end
 
   def budget_investments_chart_tag(opt = {})
-    events = events.join(",") if events.is_a? Array
     opt[:data] ||= {}
     opt[:data][:graph] = admin_api_stats_path(budget_investments: true)
     content_tag :div, "", opt