Slot allocator Javascript fix. This prevents from calling updateFromJSON function if there is no data.
Patch by: Mario Ferraro
Reviewed by: Pawel Solyga
Coverage: code coverage testing for Python
Coverage.py is a Python module that measures code coverage during test execution.
It uses the code analysis tools and tracing hooks provided in the Python standard
library to determine which lines are executable, and which have been executed.
For more information, see http://nedbatchelder.com/code/modules/coverage.html