devel/llvm60 has dependency USES= python:2.7,build. When building with DEFAULT_VERSIONS+= python=3.7, py36-setuptools is installed via dependency on py36-sphinx. Then, USES=python2.7 has implicit depencence on py27-enum which pulls in py27-setuptools. py27-setuptools and py36-setuptools conflict on /usr/local/bin/easy_install. Is there any workaround possible? It may be just a limitation with llvm60. But llvm60 affects so many ports that it is difficult to set DEFAULT_VERSIONS=python=3.6.
@Hiroo, See: bug 226634 comment 8 (and read the original bug report as well). I believe this will be the same issue as yours. I'll elaborate and extend Serges' comment to provide more detail there. If it turns out that is not the issue, let us know.
(In reply to Kubilay Kocak from comment #1) It was exactly the same problem, and rerunning poudriere was sufficient to solve it. Thank you. So, it is not an issue, sorry.
Good to hear Hiroo, thank you for following up
*** This bug has been marked as a duplicate of bug 226634 ***