for unregister.sh in all the new ghc libraries (which leads to bogus
registered ghc packages after updates).
You can use the command
ghc-pkg check
to check ghcs internal package list. If it reports missing files
for some package (like hashed-storage-0.4.11), you can forcibly
unregister it by running (as root) something like
ghc-pkg unregister hashed-storage-0.4.11
ok dcoppa@
