In some cases TMPDIR may not be set, in which case it could cause issues
for zsh modules.
This change was prompted by issue #1331.
Also when creating a missing TMPDIR, use mkdir --mode=700 instead
of creating the directory and then chmoding it afterward.
Only set up environment for the top-level shell, and allow it to be
inherited normally.
A top level shell is usually a login shell, but can also be a
non-interactive, non-login shell in certain cases, such as when
executing an SSH remote command.
Signed-off-by: Sorin Ionescu <sorin.ionescu@gmail.com>
The detection of lesspipe.sh has to be done after setting PATH as it
could be installed in a non-standard bin directory. For example,
Homebrew installs lesspipe in /usr/local.
