Invalid RPS in summary report

[richardmarshall]

Sometimes the summary report includes an invalid RPS value of -0.0000.

Example:

# latency summary
  30000       0   0.13    [0.71 10.93 20.84 64.98] 64.98  2312.19

Concurrency level: 10
Time taken for tests: 12.978338528s
Completed Requests: 30000
Failed Requests: 0
Requests per second: -0.0000 [#/sec] (mean)
Time per request: 2.42 [ms] (mean)
Fastest request: 0.13 [ms]
Slowest request: 64.98 [ms]