* Studio: guard the training import against a namespace-package shadow of unsloth
A directory named unsloth without an __init__.py on sys.path (a stray checkout,
a partial clone, or a polluted PYTHONPATH) makes the path finder return a
namespace package, so the worker's 'from unsloth import FastLanguageModel' fails
with 'cannot import name ... (unknown location)'. A normal site-packages install
always wins this race, so only source/editable installs are exposed. Before the
import, drop the offending sys.path entries, bind the real packages, then
restore sys.path so other modules on those entries keep importing. It is a
no-op when unsloth already resolves to a real package.
* Studio: import unsloth before unsloth_zoo in the namespace-shadow guard
_ensure_real_packages imported the requested names in argument order, so a
unsloth_zoo namespace shadow made it import unsloth_zoo directly before
unsloth. That skips unsloth.__init__ -> _gpu_init, which runs its ROCm and
Windows bitsandbytes fixes before its own import unsloth_zoo, so the recovery
path could import zoo with those guards skipped and fail on the ROCm/Windows
cases those fixes handle.
Import parent-first via reversed(names) so unsloth is imported first and pulls
in the real unsloth_zoo after _gpu_init has run; the later cached import is a
no-op. This also covers the case where only unsloth_zoo is shadowed: the bad
sys.path entry is still dropped and unsloth owns the zoo import. Detection,
sys.path pruning, shadow-cache clearing, and restoration are unchanged.
Add tests/test_namespace_shadow_guard_pr6269.py: CPU-only subprocess scenarios
(only zoo shadowed, both shadowed, only unsloth shadowed, healthy no-op, real
package absent, multiple shadow entries) that assert unsloth imports before
unsloth_zoo and that sys.path is restored.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
* Studio: restore sys.path even if invalidate_caches fails in the shadow guard
Move importlib.invalidate_caches() inside the try/finally so a failure there
still restores sys.path, and tighten the import-order comment. Add a test that
forces invalidate_caches to raise and asserts sys.path is restored.
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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