Issue1751

I've been trying to measure coverage of my Jython program and finding
that (at least) all lines containing "try:", "except:" or "break"
never get shown as covered.

This appears to be because the sys.settrace function, on which
coverage.py relies for its information, is not triggered by such
lines. 

For example, compare the output of the following program under Jython
and CPython. No output is created for lines 10, 12 or 13 when running
under Jython, whereas it is for CPython.

import sys

def tracefunc(frame, event, arg):
   print "Trace", event, frame.f_lineno
   return tracefunc

def do():
   x = [ 1 ]
   for i in range(2):
       try:
           x[i]
       except IndexError:
           break

sys.settrace(tracefunc)
do()

BTW, #1248 is a dup of this issue.

"with" statements are also overlooked:

import linecache, sys

def tracefunc(frame, event, arg):
    lineno = frame.f_lineno
    print "Trace", event, lineno, linecache.getline(__file__, lineno).rstrip()
    return tracefunc

def do():
    x = [ 1 ]
    for i in range(2):
        try:
            x[i]
        except IndexError:
            break

    with open(__file__) as f:
        print len(f.read())

sys.settrace(tracefunc)
do()


Produces:

Trace call 8 def do():
Trace line 9     x = [ 1 ]
Trace line 10     for i in range(2):
Trace line 10     for i in range(2):
Trace line 12             x[i]
Trace line 10     for i in range(2):
Trace line 12             x[i]
Trace exception 12             x[i]
Trace line 17         print len(f.read())
397
Trace return 17         print len(f.read())

Let's track with #1248 (try/except) and #2540 (with)