ludelete fails to delete the boot environment: mount point is already in use

While I was live upgrading from Solaris Express Community Edition build 115 to build 116 I decided to free some hard disk space and delete the oldest boot environment I had: snv_114.

That's easy:

# ludelete svn_114

But there was a small problem... ludelete complained about snv_114 unable to use its automatic mount point because the mount point was being used. Do you know what? It wasn't, before launching ludelete but, for reasons I don't understand, after mounting it it was reported as busy.

The Google Finger was going to be triggered immediately and look if there was some known bug out there but fortunately a forced unmount of the boot environmente solved the problem:

# luumount -f snv_114

Pretty strange, indeed.