copy of coverage project 3.5.2

trying to make it play nice with gevent
by simplifying trace function to ignore changes to calling stack.

======== ORIGINAL README BELOW =========

Coverage.py: code coverage testing for Python

Coverage.py measures code coverage, typically 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/coverage

Code repo and issue tracking are at http://bitbucket.org/ned/coveragepy