hdiutil: detach: timeout for DiskArbitration expired

Logs

```
$ vmdk2dmg ios-dev
==> Mount as /dev/disk3
==> Converting to image.dmg
Preparing imaging engine…
Reading Protective Master Boot Record (MBR : 0)…
(CRC32 $D0A47DAB: Protective Master Boot Record (MBR : 0))
Reading GPT Header (Primary GPT Header : 1)…
(CRC32 $EAB1CBE3: GPT Header (Primary GPT Header : 1))
Reading GPT Partition Data (Primary GPT Table : 2)…
(CRC32 $6156FAD1: GPT Partition Data (Primary GPT Table : 2))
Reading (Apple_Free : 3)…
(CRC32 $00000000: (Apple_Free : 3))
Reading EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B : 4)…
(CRC32 $E6D80B6C: EFI System Partition (C12A7328-F81F-11D2-BA4B-00A0C93EC93B : 4))
Reading Macintosh HD (Apple_HFS : 5)…
........jjjkkjkjkjkjkjkjkjkjkjkjkjk....................kkk.......................................................................................kk...........................................................
(CRC32 $E7F87F8A: Macintosh HD (Apple_HFS : 5))
Reading Recovery HD (426F6F74-0000-11AA-AA11-00306543ECAC : 6)…
................................................................................................................................................................................
(CRC32 $4CFD0502: Recovery HD (426F6F74-0000-11AA-AA11-00306543ECAC : 6))
Reading (Apple_Free : 7)…
(CRC32 $00000000: (Apple_Free : 7))
Reading GPT Partition Data (Backup GPT Table : 8)…
(CRC32 $6156FAD1: GPT Partition Data (Backup GPT Table : 8))
Reading GPT Header (Backup GPT Header : 9)…
(CRC32 $6395EE13: GPT Header (Backup GPT Header : 9))
Adding resources…
.................................................................................................................................................................................
Elapsed Time: 18m 36.567s
File size: 13600899007 bytes, Checksum: CRC32 $0A42D400
Sectors processed: 83886080, 41981716 compressed
Speed: 18.4Mbytes/sec
Savings: 68.3%
created: /Users/gitlab/workspace/osx-image/ios-dev/image.dmg
hdiutil: detach: timeout for DiskArbitration expired
```

Start by reproducing the `vmdk2dmg ios-dev` command and inspect the final `hdiutil detach` step that reports a DiskArbitration timeout. Determine the expected detach behavior and verify that conversion completes without this timeout; the issue does not mention a source file or test.

Written by the indexing model from the issue text.