Fix incorrect permissions for /etc/hosts
Fix incorrect permissions for /etc/hosts

If we modify /etc/hosts, we read/copy the ownership and permissions
from the existing /etc/hosts before we make our new temporary file
which will eventually overwrite /etc/hosts. If we fail to retrieve the
permissions of the existing /etc/hosts file, we made the temporary
file owned by root 0o600 permissions. It should have 0o644 permissions
so that /etc/hosts has the correct permissions once we rename it.

It is unlikely many encoutered this bug since most machines have
/etc/hosts prior to sshuttle running and we should be able to read the
permission/ownership of that existing file.

sshuttle/sshuttle,sshuttle/sshuttle