When upgrading binutils from 2.18.50.0.2 to 2.18.50.0.3 (on x86-solaris2.10) I get an error which (although in prefix) seems to be related to feature 'preserve-libs' (detailed error and 'emerge --info' attached). It seems portage wants to preserve a sharedlib in a directory containing $PV, which (not surprisingly) does not exist in the new package any more, but does not create the old directory in the new package.
Created attachment 138251 [details] detailed error message, and 'emerge --info' output
Looks like Zac fixed it already in r9230
ah, stupid, indeed, this bug was fixed when I hit the same problem on FreeBSD :)