Bug#157102: shell not correctly asigned to user vpopmail

[Eduard Llull <ellull@teleline.es>]

Package: vchkpw
Version: 3.1.2-9

When you install the vchkpw package, the vpopmail user is created with shell 
in /etc/passwd set to /bin/false. This should be ok, but the same package 
adds a cron job: /etc/cron.daily/vchkpw that does:
su - vpopmail -c /usr/lib/vchkpw/vchkexpire
If vpopmail user has the shell set to /etc/false, how is supposed the 
/usr/lib/vchkpw/vchkexpire script to be executed?

I can think two possible solutions:
1- Set the vpopmail shell to /bin/sh
2- Modify the cron job to be executed as root removing the su stuff