The macOS DiskImage unit tests intermittently failed in CI with:
System.InvalidOperationException : Process diskutil with arguments
eject /dev/rdiskN exited with code 1: Volume failed to eject
ReAttach() and CleanupDisk() called `diskutil eject` directly while a
volume could still be busy right after writing, so the eject transiently
failed (e.g. Test_GPT_FAT32_FAT32_FAT32_Async). This is test-infrastructure
only; no product code is affected.
Add a shared EjectDisk() helper that flushes buffers (sync), force-unmounts
all volumes first, then ejects with exponential backoff (reusing
Utility.GetRetryDelay), falling back to a forced `hdiutil detach` of the
image-backed device. Also make Unmount() force-unmount and return on success.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
