[metrics-bugs] #25397 [Metrics/Website]: Cut off lower number of expected clients at 0

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#25397: Cut off lower number of expected clients at 0
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     Reporter:  karsten          |      Owner:  metrics-team
         Type:  defect           |     Status:  new
     Priority:  Medium           |  Milestone:
    Component:  Metrics/Website  |    Version:
     Severity:  Normal           |   Keywords:
Actual Points:                   |  Parent ID:
       Points:                   |   Reviewer:
      Sponsor:                   |
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 We should avoid negative numbers in clients.csv and in per-graph CSV files
 based on it.

 Take this graph as example:

 https://metrics.torproject.org/userstats-relay-
 country.html?start=2013-08-15&end=2013-08-31&country=dk&events=on

 The corresponding CSV file is:

 {{{
 date,users,downturns,upturns,lower,upper
 2013-08-15,2419,FALSE,FALSE,1509,3400
 2013-08-16,2417,FALSE,FALSE,1530,3526
 2013-08-17,2583,FALSE,FALSE,1888,3593
 2013-08-18,2625,FALSE,FALSE,2099,3451
 2013-08-19,2631,FALSE,FALSE,1950,3865
 2013-08-20,2998,FALSE,FALSE,-307,8058
 2013-08-21,3429,FALSE,FALSE,-2158,12097
 2013-08-22,4161,FALSE,FALSE,-5815,19493
 2013-08-23,4910,FALSE,FALSE,-11092,29505
 2013-08-24,5387,FALSE,FALSE,-14669,35722
 2013-08-25,5899,FALSE,FALSE,-16103,38944
 2013-08-26,6115,FALSE,FALSE,-18394,42370
 2013-08-27,6486,FALSE,FALSE,-8958,29056
 2013-08-28,7213,FALSE,FALSE,-4772,23752
 2013-08-29,7950,FALSE,FALSE,-1111,19506
 2013-08-30,8844,FALSE,FALSE,1660,17111
 2013-08-31,9966,FALSE,FALSE,2088,19165
 }}}

 We can just cut the lower number at 0. Like in the graph.

 We could do it in write_userstats_relay_country() or in the clients
 module. The first is at lot easier to fix.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25397>
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