Description:
------------
I am trying to build PHP 5.2.5 for an RPM, on a system which already 
has PHP 5.2.4 installed (I built that RPM several months ago).  In 
order to build the RPM, I need to make and install into a temporary 
local directory, as an unprivileged user.  The build fails with this 
error:

Installing PEAR environment:      /hlg/rpmbuild/buildroot/php-5.2.5-1-
manual/usr/local/lib/php/download directory "/tmp/pear/cache" is not 
writeable.  Change download_dir config variable to a writeable dir
 ...

... followed by a series of related errors, and resulting in an 
incomplete install tree.

I think this bug someone filed with debian.org is the same problem:
  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463979


Note: php.net directed me to file PEAR-related bugs on the PEAR web 
site; however, their bug system seems to only want bugs about to 
specific pear packages, so this problem did not seem to fit there.

Reproduce code:
---------------
Unpack PHP tarfile.
Configure it with the --with-pear option.

# mkdir -p /rpmbuild/buildroot/php-5.2.5-1-manual/etc/httpd/conf/
# cp -p /etc/httpd/conf/httpd.conf /rpmbuild/buildroot/php-5.2.5-1-manual/etc/httpd/conf/
# make INSTALL_ROOT=/rpmbuild/buildroot/php-5.2.4-4-manual install



Expected result:
----------------
I expect a complete PHP install tree, with PEAR, in 
/rpmbuild/buildroot/php-5.2.5-1-manual/

Actual result:
--------------
Installing PHP SAPI module:       apache2handler
/usr/lib/httpd/build/instdso.sh SH_LIBTOOL='/bin/sh 
/usr/lib/apr/build/libtool' libphp5.la /rpmbuild/buildroot/php-5.2.4-
4-manual/usr/lib/httpd/modules
/bin/sh /usr/lib/apr/build/libtool --mode=install cp libphp5.la 
/rpmbuild/buildroot/php-5.2.4-4-manual/usr/lib/httpd/modules/
cp .libs/libphp5.so /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/lib/httpd/modules/libphp5.so
cp .libs/libphp5.lai /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/lib/httpd/modules/libphp5.la
libtool: install: warning: remember to run `libtool --finish 
/home/cos/php-5.2.4/libs'
chmod 755 /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/lib/httpd/modules/libphp5.so
[activating module `php5' in /rpmbuild/buildroot/php-5.2.4-4-
manual/etc/httpd/conf/httpd.conf]
Installing PHP CLI binary:        /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/bin/
Installing PHP CLI man page:      /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/man/man1/
Installing build environment:     /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/lib/php/build/
Installing header files:          /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/include/php/
Installing helper programs:       /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/bin/
  program: phpize
  program: php-config
Installing man pages:             /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/man/man1/
  page: phpize.1
  page: php-config.1
Installing PEAR environment:      /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/lib/php/
download directory "/tmp/pear/cache" is not writeable.  Change 
download_dir config variable to a writeable dir
[PEAR] Console_Getopt: Cannot initialize 'phar://install-pear-
nozlib.phar/Console_Getopt-1.2.3.tar', invalid or missing package file
download directory "/tmp/pear/cache" is not writeable.  Change 
download_dir config variable to a writeable dir
[PEAR] Archive_Tar: Cannot initialize 'phar://install-pear-
nozlib.phar/Archive_Tar-1.3.2.tar', invalid or missing package file
download directory "/tmp/pear/cache" is not writeable.  Change 
download_dir config variable to a writeable dir
[PEAR] Structures_Graph: Cannot initialize 'phar://install-pear-
nozlib.phar/Structures_Graph-1.0.2.tar', invalid or missing package 
file
download directory "/tmp/pear/cache" is not writeable.  Change 
download_dir config variable to a writeable dir
[PEAR] PEAR: Cannot initialize 'phar://install-pear-nozlib.phar/PEAR-
1.6.1.tar', invalid or missing package file
Installing PDO headers:          /rpmbuild/buildroot/php-5.2.4-4-
manual/usr/local/include/php/ext/pdo/

(also at http://pastebin.com/f5c6ff39a )