Some folks out there use the --usepkg option as a default option for emerge (together with buildpkg-FEATURE, for example). But if revdep-rebuild finds broken linkage, then it would be useless to just extract the same broken files again from a tbz2. So --usepkg=n should be used to call emerge from revdep-rebuild.
Steps to Reproduce:
1. emerge some packages with buildpkg FEATURE enabled
2. get an update for some package which will eventually break linkages to other packages
3. call revdep-rebuild with --usepkg being in EMERGE_DEFAULT_OPTS
The tbz2-binary of the found packages will be extracted, including the already-broken files. This renders the use of revdep-rebuild useless.
The package should be completely recompiled to get the linkages right. So to speak like one had called: "revdep-rebuild -- --usepkg=n". I don't see a reason why this shouldn't be the case by default.
Excerpt from my said configuration:
EMERGE_DEFAULT_OPTS="... --usepkg ..."
FEATURES="... buildpkg ..."
*** This bug has been marked as a duplicate of bug 333285 ***