[CentOS] Building php-5.1.2-5 and php-pear-5.1.2-5 rpms

I want to build the php-5.1.2-5  and php-pear-5.1.2-5
from the fedora  devel SRPM's on CentOS 4.3. Whilst
the php-5.1.2-5 builds from the php-5.1.2-5 SRPM, the
1.4.6-2 php-pear builds a php-pear-1.4.6-2 instead of
php-pear-5.1.2-5

What am i doing wrong? 

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