weird bug in rebuilding RPMs

Hello,

I'm a long time user and I had always installed postgres by compiling
from source.
I recently moved to a new environment where everything is installed as
rpm and plus
I need to install a newer postgres for testing while keeping the
existing version in place.
That leads me to repackage postgres rpm.

Because I will eventually be installing red hat rpm I take their
latest srpm and modify their rpm spec file
in order to let me install rpm. After trials and errors I have
managed to rebuild rpm to my satisfaction
but would like to report a minor bug.

I can now rebuild rpms so that all files go under a specific directory
specified by _prefix directive in ~/.rpmmacros
Forgetting lots of other bugs that I managed to fix, this weird bug is
making me use _prefix that does not include
the word "pgsql" in the path name any where. For example if _prefix
path has the word pgsqL or pgsq or pgsqA then rebuilding is successful
but if the path includes the word pgsql or pgsql-8.1.18 or pgsqll then
rebuilding breaks down.

It is failing at install stage. This is the command.
$ rpmbuild --bi spec
I always do "rpmbuild --clean spec" before any rebuilding.

What follows is the error message before it quits (prefix is
/usr/local/pgsql/bla)
-------------
make: Leaving directory `/home/me/build/BUILD/postgresql-8.1.18/contrib/xml2'
+ case `uname -i` in
++ uname -i
++ uname -i
+ mv /var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/include/pg_config.h
/var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/include/pg_config
_x86_64.h
+ install -m 644 /home/me/build/SOURCES/pg_config.h
/var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/include
++ uname -i
+ mv /var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/include/pgsql/server/pg_config.h
/var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/incl
ude/pgsql/server/pg_config_x86_64.h
mv: cannot stat
`/var/tmp/postgresql-8.1.18-2.1-root//usr/local/pgsql/bla/include/pgsql/server/pg_config.h':
No such file or directory
error: Bad exit status from /var/tmp/rpm-tmp.56667 (%install)

RPM build errors:
Bad exit status from /var/tmp/rpm-tmp.56667 (%install)
-------------
If any one else would find it useful, I can also post a diff of the
spec file which will make it possible for repackaging and including
renaming so that it does not override the existing version. Other
bugs I encountered are of the nature: paths that should not be
hard-coded are hard-coded and vice versa.

Thanks

mr.wu