There are few build scripts which set them to `nodtd.invalid` to disable
downloading files by buildscript. But for user environment we should
restore original values
First I don't think there is a reason to run shell as a child of
load-env-xxx script and not to just exec into it.
Also it's often useful to just run a command inside the environment
load-env-xxx command --args
Closes #3254
As zsh's corresponding flag is called --no-rcs, the build environment
couldn't be configured to use zsh at all.
Even then the custom PS1 won't work on zsh, but it's usable enough.
Close #1040.
This option allows the user to specify commands to run when the shell
exits. This can be used to cleanup operations done in `extraCmds'.
Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
