envd: Host file disclosure through requirements path traversal and TOCTOU
envd’s install.python_packages(requirements=…) could read files outside the build context on the host. Content interpreted as dependency entries could appear in build logs and build-step metadata. Commit f576c92, released in v1.3.5, added path containment validation but left a time-of-check/time-of-use (TOCTOU) race between symlink resolution and opening the requirements file. Commit 9d575b3 addresses this race by opening requirements files through a directory-rooted filesystem handle.