[Mailman-Developers] Upgrading from Mailman 3.0 installed with mailman-bundler: sassc error

[Terri Oda]

Hit an issue while upgrading mailman bundler that I'm just going to note 
here in case it affects anyone else.

After upgrading, I go to the web interface and try to log in only to get 
the following error:
“/bin/sh: sassc: command not found”

Which as a security person is the type of error message I least like 
seeing, but that's another story. ;)

This thankfully made me think of the last commit message in 
mailman-bundler, and the commits helped me figure out the rest:

https://gitlab.com/mailman/mailman-bundler/commit/3d6555acd640d77f510b786e5ebae379c73cf6bd

the solution is
1. install rubygem-sass
2. update mailman_web/development.py so that COMPRESS_PRECOMPILERS asks 
for sass instead of sassc

I'm sure I'm going to find a few more bugs as I go, but I wanted to note 
that one before I forgot.

  Terri