I don't believe it does get overwritten - it should be marked as a config file in the rpm spec file so if you have modified it, the new install should create a /etc/php.ini.rpmnew file [by TrevorH]
on 11/21/2012 – Made popular on 11/21/2012
After upgrading to version 21 of Fedora OS, I was issued sendmail.cf.rpmnew and submit.cf.rpmnew files. Since sendmail uses .mc files to generate new configuration, I was expecting to receive sendmail.mc.rpmnew instead. Judging from this thread on Redhat, it seems like a long standing issue.
My question is, what can be done after receiving .cf.rpmnew that is different from my existing .cf file?