dependency.missingslot 1 www-apps/piwik/piwik-2.16.2.ebuild: RDEPEND: 'virtual/httpd-php' matches more than one slot, please specify an explicit slot and/or use the := or :* slot operator (This is from an overlay, but presumably it would apply to all ebuilds using depend.php?)
Nothing should be using depend.php.eclass as it is scheduled for removal as soon as bug 552836 and bug 552838 are solved. It is unfortunate that all overlays don't keep up with the announcements or become stale.
I think we're only waiting on one more package (websvn) before removing depend.php entirely. You'd better just get rid of it. It doesn't do anything special, you can replace it with a standard dev-lang/php:slot[flags] dep.
Okay, sorry! Thanks for the suggestion.