the scenario I had was as follows (using opam 1.2.2):

• opam update in the working directory /tmp/foo
• rm -rf /tmp/foo in a different terminal

I was surprised that during the update (while opam was downloading), opam complained about "no such file or directory" -- which I then discovered was related to the current working directory which got lost.

--> why does opam need to investigate its cwd (and check existance) while it is downloading things to ~/.opam?