Wrongly treat statement as uncovered

[whoiscc]

Reproduction:

class A:
    def __init__(self, xs):
        self._xs = xs

    def __getitem__(self, x):
        return x in self._xs


a1 = A([10])
a2 = A(list(range(42)))

for i in range(42):
    for j in range(42):
        if not a1[i] or not a2[j]:
            continue

After running coverage run test.py and coverage report -m:

Name      Stmts   Miss  Cover   Missing
---------------------------------------
test.py      11      1    91%   15

And line 15 is the single continue statement. If I add a print('continue') above it, tons of "continue" will be printed, and coverage report correctly back to 100%.

[nedbat]

This report is a duplicate of #198. It's a limitation of CPython's peephole optimizer, described in https://bugs.python.org/issue2506