MODULEPATH broken across different shell invocations, due to poor package delivery for env. modules

Dear GCP,

Here is an example of the bug manifestation.

Would you agree that the duplications and arbitrary ordering across different shell variants is a bug?

```
mkdir -p /tmp/hello; module use /tmp/hello ; for i in sh csh tcsh zsh ksh bash "bash -l"; do echo == SHELL is $i; echo 'echo $MODULEPATH'| $i ; done
== SHELL is sh
/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is csh
/etc/scl/modulefiles:/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is tcsh
/etc/scl/modulefiles:/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is zsh
/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is ksh
/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is bash
/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
== SHELL is bash -l
/etc/scl/modulefiles:/tmp/hello:/etc/scl/modulefiles:/usr/share/Modules/modulefiles:/etc/modulefiles:/usr/share/modulefiles:/opt/apps/modulefiles
```