I know it's not keyworded but hey, it's still a bug ;)
>>> Installing (1 of 1) sys-devel/automake-1.13.1
* checking 124 files for package collisions
* This package will overwrite one or more files that may belong to other
* packages (see list below). You can use a command such as `portageq
* owners / <filename>` to identify the installed package that owns a
* file. If portageq reports that only one package owns a file then do
* NOT file a bug report. A bug report is only useful if it identifies at
* least two or more packages that are known to install the same file(s).
* If a collision occurs and you can not explain where the file came from
* then you should simply ignore the collision since there is not enough
* information to determine if a real problem exists. Please do NOT file
* a bug report at http://bugs.gentoo.org unless you report exactly which
* two packages install the same file(s). Once again, please do NOT file
* a bug report unless you have completely understood the above message.
* package sys-devel/automake-1.13.1 NOT merged
* Detected file collision(s):
* Searching all installed packages for file collisions...
* Press Ctrl-C to Stop
* Package 'sys-devel/automake-1.13.1' NOT merged due to file collisions.
* If necessary, refer to your elog messages for the whole content of the
* above message.
This is supposed to be already fixed in the tree.