Cancel analysis not working on OSX

[jorgegil]

The Graph Analysis cancel button does not stop an analysis running in the background. This was observed on MacOSX using QGIS 2.18.
The GA tool interrupts the process, allows a new analysis to be initiated, but the previous analysis is still running. (visible if the terminal window is open)
After it finishes, the first analysis might continue to run in the background until finished. It will not report the results.