dev-util/cvs installs a file /usr/share/emacs/site-lisp/cvs-format.el. The file contains definitions for a C indentation style. It is not loaded by default, but the user must activate it manually. In any case, it is not very useful to have it in the site-lisp directory. Also, when loading it, the standard C indentation will be clobbered. I propose to get rid of the emacs USE flag and not install the file. Or it could be installed under /usr/share/doc/ instead. Patch will follow.
Created attachment 153281 [details, diff] Proposed change for cvs-1.12.13.1.ebuild
Fixed in CVS.