bug: asdf global ... system needs write access to the entire HOME directory when .tool-versions already exists there

[lestephane]

Describe the Bug

I removed write access on my $HOME a long time ago, to explicitly allowlist the files / directories required by the tools I use, and to avoid the tools that have weird or unenforcable writing habits.

Asdf looks like it needs write access to the home directory because it uses sed -i to modify .tool-versions when .tool-versions exists

$ asdf global python system
sed: couldn't open temporary file /home/lestephane/sedWp3RW1: Permission denied

I'd expect write access to .tool-versions is all asdf needs for me to run this command.

Steps to Reproduce

$ truncate -s 0 $HOME/.tool-versions
$ chmod a-w $HOME
$ asdf global python system
$ asdf global python system
sed: couldn't open temporary file /home/lestephane/sediRUEgd: Permission denied

Expected Behaviour

No error on the second call to asdf global python system

Actual Behaviour

Second call fails

Environment

...
ASDF VERSION:
v0.11.3
...

asdf plugins affected (if relevant)

N/A

[hyperupcall]

When #1351 is fully implemented (right now it isn't), this will be addressed because the global .tool-versions will be in a asdf-specific directory (with only a few files).