Handle while True loops without break statements

[kreathon]

Description

In the following example, the print statement is not recognized as unreachable code by vulture.

while True:
    raise Exception()
print("Currently not recognized!")

More general: If a while True statement has no break, then the statement after the while True is unreachable.

Implementation

Introduce self._current_loop_has_break_statement in order to keep track of break statements found while traversing the AST.

We cannot validate if the break statements only occur in loops (so we need to assume the code is correct). In order to check this properly, we would need to visit the parent first (and push some kind of context or scope; pop if after visiting the children).

Checklist

• I have updated the documentation in the README.md file or my changes don't require an update.
• I have added an entry in CHANGELOG.md.
• I have added or adapted tests to cover my changes.
• I have run pre-commit run --all-files to format and lint my code.

[jendrikseipp]

The code is flawless. Thanks for the PR!