thefuck_contrib_* packages are exec'd before enable-gating on every run

Description

corrector.get_rules_import_paths() (thefuck/corrector.py) scans every sys.path entry for thefuck_contrib_* packages and yields their rules/ directories. Rule.from_path (thefuck/types.py) then load_source's (executes) each rule module before any is_enabled / settings gating is applied — the enabled-by-default functions in rules only run later, but the module top-level code has already executed at import time.

So any writable sys.path entry (a shared virtualenv, group-writable site-packages directory, or an attacker-planted thefuck_contrib_* package) results in code execution for every user who runs any thefuck command on that interpreter — regardless of their rules configuration.

Impact

On shared multi-user machines (shared venvs, group-writable site-packages, or any scenario where a lower-privileged user can write into a sys.path entry used by another user's interpreter), a local user obtains code execution in every other user's thefuck invocation with that interpreter. On single-user machines this reduces to ordinary package-integrity trust and is not a boundary crossing — the report is about the shared-host case, and about the fact that the enable-gating documented in the rules system does not actually gate imports.

PoC

Verified on thefuck 3.32 (source install). Drop a contrib package into the interpreter's site-packages (structure required by get_rules_import_paths):

site-packages/thefuck_contrib_evil/rules/evil.py:
    open('/tmp/thefuck_contrib_pwned', 'w').write('executed before enable-gating')
    def match(command):
        return False            # never matches; irrelevant — import already ran

Victim runs any correction:

thefuck "git statsu"

Execution result

[evidence] contrib module side effect ran: True
[evidence] side-effect file content: executed before enable-gating

The module executed during rule loading, before any enable/disable decision could apply.

Suggested fix direction: defer load_source until after the rule's is_enabled/settings check, or restrict contrib discovery to explicitly configured paths.