suite à emerge busybox :

>>> Merging sys-apps/busybox-1.2.1 to /
 * setting USE=make-symlinks and emerging to / is very dangerous.
 * it WILL overwrite lots of system programs like: ls bash awk grep (bug 60805 for full list).
 * If you are creating a binary only and not merging this is probably ok.
 * set env VERY_BRAVE_OR_VERY_DUMB=yes if this is realy what you want.

!!! ERROR: sys-apps/busybox-1.2.1 failed.
Call stack:
  ebuild.sh, line 1562:   Called dyn_preinst
  ebuild.sh, line 1038:   Called pkg_preinst
  busybox-1.2.1.ebuild, line 243:   Called die

!!! silly options will destroy your system
!!! If you need support, post the topmost build error, and the call stack if relevant.

!!! FAILED preinst: 1