Setup creates the mount point before weed mount starts, so statting and
listing it succeeded on the plain directory and tests ran against local
disk whenever the mount was slow or died. waitForMount now waits until the
mount point's device id differs from its parent's.
Generated with [Devin](https://devin.ai)
Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
