net-libs/gnutls with USE=-doc installs useless png files in doc dir. They needed only by gnutls.html, which only get installed with USE=doc. I tried -3.3.6 and -3.3.7. With USE=doc: # qlist gnutls | grep /usr/share/doc/gnutls-3.3.7/html/ /usr/share/doc/gnutls-3.3.7/html/gnutls-client-server-use-case.png /usr/share/doc/gnutls-3.3.7/html/gnutls-handshake-sequence.png /usr/share/doc/gnutls-3.3.7/html/gnutls-handshake-state.png /usr/share/doc/gnutls-3.3.7/html/gnutls-internals.png /usr/share/doc/gnutls-3.3.7/html/gnutls-layers.png /usr/share/doc/gnutls-3.3.7/html/gnutls-logo.png /usr/share/doc/gnutls-3.3.7/html/gnutls-modauth.png /usr/share/doc/gnutls-3.3.7/html/gnutls-pgp.png /usr/share/doc/gnutls-3.3.7/html/gnutls-x509.png /usr/share/doc/gnutls-3.3.7/html/gnutls.html /usr/share/doc/gnutls-3.3.7/html/pkcs11-vision.png With USE=-doc: # qlist gnutls | grep /usr/share/doc/gnutls-3.3.7/html/ /usr/share/doc/gnutls-3.3.7/html/gnutls-client-server-use-case.png /usr/share/doc/gnutls-3.3.7/html/gnutls-handshake-sequence.png /usr/share/doc/gnutls-3.3.7/html/gnutls-handshake-state.png /usr/share/doc/gnutls-3.3.7/html/gnutls-internals.png /usr/share/doc/gnutls-3.3.7/html/gnutls-layers.png /usr/share/doc/gnutls-3.3.7/html/gnutls-logo.png /usr/share/doc/gnutls-3.3.7/html/gnutls-modauth.png /usr/share/doc/gnutls-3.3.7/html/gnutls-pgp.png /usr/share/doc/gnutls-3.3.7/html/gnutls-x509.png /usr/share/doc/gnutls-3.3.7/html/pkcs11-vision.png
Fixed in gnutls-3.3.7-r1, thanks!