Apparently, it is possible to set up a Mac such that
`scutil --get ComputerName` hasn't been set.
This change checks if that fails and falls back to the original
mechanism.
Closes#2155Closes#2183
On an OS X laptop, the variable `$HOST` changes a lot depending
on what wifi network you're connected to. This causes a lot
of `~/.ssh/environment-$HOST` files to be created and
causes multiple ssh-agents to created.
Instead, use `scutil --get ComputerName` to get something
more stable.
This will prevent lots of subtle problems that happen when
people upgrade ZSH or use NFS mounted home directories.
The ZSH_COMPDUMP variable can also be used to implement `zcompile`
and other fun features in the future.