How to reproduce:
man 5 ebuild
It says about execinto at the doexe description. The correct would be exeinto.
Tested with sys-apps/portage-126.96.36.199 (the latest stable version)
Thanks, this is fixed in git now:
This is in 2.2_rc68, but I'll leave this bug open until it's in an unmasked version.
This is fixed in 2.1.9.