When the /usr/portage directory is missing and users uses --sync for first time the portage is pulled as expected. However when the directory is there but empty it fails to fetch it with no relevant error message and a returncode of 0.
This works with sys-apps/portage-18.104.22.168, so it's a regression in 2.2
This is fixed in 2.2.5.
*** Bug 487156 has been marked as a duplicate of this bug. ***
respectfully, this isn't "RESOLVED" until a stable portage version has the fix. Our stages are shipping a broken portage.
2.2.7 is stable -> FIXED