See https://github.com/gentoo/gentoo/pull/32424#discussion_r1306177444. The pam ebuild downloads a docs tarball which extracts into docs/ in the source tree but the tarball only seems to contain HTML which we don't seem to install. Not sure if in the past it had man pages too (they seem to be in the src tarball itself now). We should either wire up USE=doc here so it actually installs these, install them unconditionally (meh given it's pam and always around), or stop downloading it.