Branches shown where there are none

[jaltmayerpizzorno]

Describe the bug
coverage.py detects (executed and/or missing) branches where really there are none.

To Reproduce
coverage.py shows branches for the excerpts below where there are none; I can reproduce these issues with various version of Python (with some differences), including Python 3.11 and 3.12. I'm using coverage.py v7.3.2.

• comprehensions/generators:

a = [n for n in range(10)]
b = {n for n in range(10)}
c = {n:n for n in range(10)}
z = sum(n for n in range(10))

yields:

Name               Stmts   Miss Branch BrPart  Cover   Missing
--------------------------------------------------------------
comprehension.py       4      0      8      0   100%
--------------------------------------------------------------
TOTAL                  4      0      8      0   100%

• decorated def:

def foo(x):
    return x

@foo
def bar(y):
    return y

yields:

Name               Stmts   Miss Branch BrPart  Cover   Missing
--------------------------------------------------------------
decorated-def.py       5      1      2      0    86%   6
--------------------------------------------------------------
TOTAL                  5      1      2      0    86%

• with statement:

with open("with.py") as f:
    x = len(f.readlines())

y = 0

yields:

Name      Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------
with.py       3      0      2      0   100%
-----------------------------------------------------
TOTAL         3      0      2      0   100%

• multiline if:

def foo(x):
    if (x >= 10
        and x > 0
    ):
        return True

foo(10)

yields (in the JSON):

            "executed_branches": [
                [
                    2,
                    2
                ],
                [
                    2,
                    5
                ]
            ],
            "missing_branches": [
                [
                    2,
                    -1
                ]
            ]

• exception handling:

try:
    raise RuntimeError("oops")

except RuntimeError:
    # nothing here
    x = 42

except Exception:
    x = 666

yields (in the JSON):

            "executed_branches": [
                [
                    4,
                    6
                ]
            ],
            "missing_branches": [
                [
                    4,
                    8
                ]
            ]

Each of these was generated with:

P="python3.11"
for f in *.py; do
    $P -m coverage run --branch $f
    $P -m coverage report -m
    $P -m coverage json --pretty-print -o `basename -s .py $f`.json
done

with.json
multiline-if.json
exception.json
decorated-def.json
comprehension.json