For http://bugs.gentoo.org/287976, A news item:

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Title: Usage of default-linux as profile is obsolete
Author: Samuli Suominen <ssuominen@g.o>
Content-Type: text/plain
Posted: 2009-10-21
Revision: 1
News-Item-Format: 1.0
Display-If-Profile: default-linux

The profiles in default-linux/ have been deprecated for a while now, and
you have been seeing a message of profile switching when using emerge.

They will be entirely removed 2009-12-01. This is your last warning to
switch into new profiles using:

# eselect profile list
# eselect profile set <target>

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Would this work?