When portage-2.2_rc43 is emerged with USE=python3, the fetch command (and some other related things like checksum tests) do not recognize that the output is a terminal leading to the same effect as described in bug 241100. With USE=-python3 the problem does not arise, i.e. it seems to be a python3 compatibility issue. portage-2.2_rc_42 had the same problem.
Support for pty is disabled as a workaround for http://bugs.python.org/issue5380.
We're using a runtime check to detect issue 5380 and disable pty support, so there's nothing left to do on our side other than get it fixed in python.
*** Bug 288036 has been marked as a duplicate of this bug. ***
This is fixed in git: http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=1c0996eea7a39ef0357b5ece630c1bdf69680f71
This is fixed in 2.1.9.35 and 2.2.0_alpha19.