Courier IMAP - vpopmail troubles

I like the qmail/vpopmail solution as a email server a lot and use it in lots of places. Usually there is only one domain, but in one special case I had to create more than one. I also use courier-imap as imap/pop3 daemon because of its support for vpopmail.
So last week I went to create a new virtual domain on this site and at first all seemed to work fine, but after a while users on the new virtual domains reported login errors.
After some googling I searched the vpopmail mailing lists and found the following posts:

http://www.mail-archive.com/vchkpw@inter7.com/msg09933.html
http://www.mail-archive.com/vchkpw@inter7.com/msg09943.html

Since I usually install qmail on SuSE linux systems I wanted to modify the rpm of courier-imap (version 3.0.8) so that it would also build the needed authvchkpw . This turned out not to be easy and required a modification to the spec file that I am attaching here:

--- courier-imap.spec.orig      2005-03-21 09:51:21.000000000 +0100
+++ courier-imap.spec   2005-03-22 16:45:34.544423142 +0100
@@ -317,6 +317,11 @@

%{__chmod} 555 $RPM_BUILD_ROOT%{_datadir}/sysconftool-rpmupgrade

+# (Umberto, Prometeo SRL 2005)
+# Make sure authvchkpw gets copied int libexec/authlib
+#
+cp -f authlib/authvchkpw $RPM_BUILD_ROOT%{_libexecdir}/authlib
+
#
#  Check if authdaemond was installed, make sure to include authdaemon
#  directory
@@ -469,6 +474,7 @@

%dir %{_libexecdir}
%dir %{_libexecdir}/authlib
+%attr(755, root, root) %{_libexecdir}/authlib/authvchkpw
%dir %{_sysconfdir}
%dir %{_sysconfdir}/shared
%dir %{_sysconfdir}/shared.tmp

To use it simply extract the courier-imap.spec file in rpm/SPECS and patch it. Then move the courier imap sources in rpm/SOURCES and build normally.
These are the directions for building courier rpms:
http://www.courier-mta.org/FAQ.html#rpm

Cheers,
Umberto