$ rpm --rebuild findutils-4.1.4-1.src.rpm
....
%install stage
...
make[2]: Entering directory `/usr/mjt/rpm/build/findutils-4.1.4/locate'
/bin/sh ../mkinstalldirs /var/tmp/find-root/usr/bin
  /usr/bin/install -c  locate /var/tmp/find-root/usr/bin/locate
/bin/sh ../mkinstalldirs /usr/lib/findutils
mkdir /usr/lib/findutils
^^^^^^^^^^^^^^^^^^^^^^^^
mkdir: cannot make directory `/usr/lib/findutils': Permission denied
make[2]: *** [install-libexecPROGRAMS] Error 1

$_

This caused by buggy line in locate/Makefile, at the bottom of file,
that is a duplicate of install target (install: install-am):
---
install:
        $(top_srcdir)/mkinstalldirs $(localstatedir)
---

And also, relevant portion of .spec file:
===========
%define optflags $RPM_OPT_FLAGS -D_GNU_SOURCE
%configure \
 --exec-prefix=%{_prefix} \
 --libexecdir=$RPM_BUILD_ROOT/%{_prefix}/lib/findutils
%undefine optflags

make localstatedir=/var/lib

%install
rm -rf $RPM_BUILD_ROOT
mkdir -p ${RPM_BUILD_ROOT}%{_prefix}/lib/findutils
make \
 prefix=${RPM_BUILD_ROOT}%{_prefix} \
 exec_prefix=${RPM_BUILD_ROOT}%{_prefix} \
 libexecdir=%{_prefix}/lib/findutils \
 localstatedir=/var/lib \
 install
===

This should be as follows:
===
%define optflags $RPM_OPT_FLAGS -D_GNU_SOURCE
%configure \
 --exec-prefix=%{_prefix} \
 --libexecdir='${exec_prefix}/lib/findutils' \
 --localstatedir=/var/lib
%undefine optflags

make

%install
rm -rf $RPM_BUILD_ROOT
#mkdir -p ${RPM_BUILD_ROOT}%{_prefix}/lib/findutils
make install DESTDIR="${RPM_BUILD_ROOT}"
======

Far more clean than original (RH) verion... ;)

==
Can anybody audit all packages to be buildable as non-root and
thus preventing that ugly bug(s)?!
I already posted tons of bugreports about similar problems
(missing `%defattr(-,root,root)', stupid `install -u0 -g0',
modification of system files when building etc etc...)