you cannot set the $P variable inside of an ebuild but the following do:
dev-php/PEAR-Cache/PEAR-Cache-1.5.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Log/PEAR-Log-1.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Log/PEAR-Log-1.2.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Mail_Mime/PEAR-Mail_Mime-1.2.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Net_Sieve/PEAR-Net_Sieve-0.8.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Net_Socket/PEAR-Net_Socket-1.0.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-System_Command/PEAR-System_Command-1.0.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-XML_CSSML/PEAR-XML_CSSML-1.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-XML_Tree/PEAR-XML_Tree-1.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-XML_XPath/PEAR-XML_XPath-1.2.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-Date/PEAR-Date-1.3.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-HTML_Common/PEAR-HTML_Common-1.0.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-HTML_Select_Common/PEAR-HTML_Select_Common-1.1.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-DB/PEAR-DB-1.3.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-HTML_QuickForm/PEAR-HTML_QuickForm-2.10.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-HTML_Template_Flexy/PEAR-HTML_Template_Flexy-0.4.ebuild:P=${PN/PEAR-//}-${PV}
dev-php/PEAR-HTML_Template_Sigma/PEAR-HTML_Template_Sigma-1.0.ebuild:P=${PN/PEAR-//}-${PV}
