Steps to reproduce:
1) make it so that /usr/portage/distfiles does not contain useful files (i.e. that would not be removed by eclean-dist), but contains at least one file.
2) run eclean-dist or eclean-dist --deep
3) observe that /usr/portage/distfiles directory is no longer present
This is not a problem for portage itself (it will recreate this directory as needed), but subsequently running eclean-dist or eclean-pkg will give error like
!!! /usr/portage/distfiles does not appear to be a directory.
!!! Please set DISTDIR to a sane value.
!!! (Check your make.conf file and environment).
Expected result: eclean-dist does not break subsequent run of eclean-pkg, by either not removing the distfiles directory or by eclean-pkg not generating error out of this.
(gentoolkit-0.4.8 seems to have the same problem.)
I can also reproduce this bug with app-portage/gentoolkit-0.5.0.