Simplification of the code by replacing iperf_opt by target_bitrate (returned from Iperf_ComputeModifiedBW) - no need to repeat the steps to retrieve information about requested bitrate from iperf_opt. Compute iperf bitrate performance as receiver bitrate over requested (target) bitrate.
Fix an issue with misdetection of missing report line - "result" was defined 2x in the function. With this MR, result can be only None or stores output of re.search() for matching the report line pattern, which ensure proper detection of the report line as well as presence off all required components in the report line.