apt-get bug w.r.t. invoke-rc.d: how to report a bug

Not a question, but a bug to report. How do I report a bug.

When attempting any apt-get *grub* request I get:

invoke-rc.d: not a symlink: "/etc/rc2.d/S99grub-common"
invoke-rc.d: dangling symlink: "/etc/rc2.d/S99grub-common"

There does not appear to be a invoke-rd.d anywhere in /etc
Therre is a rc2.d/S99grub-common which is a link to ../init.d/grub-common

I tried:

apt-get remove grub-common

but it failed.

-- david