I just reinstalled db and got the following error: ERROR: test You must have USE=tcltk to run the sys-libs/db testsuite. Two things: 1) db does not use tcltk as a USE-flag anymore, it uses tcl. 2) if other packages are needed to be able to do FEATURES="test" then there should be a test USE-flag depending on this packages.
I've changed the eclass to look for tcl instead of tcltk. I've also added tcl as a test dep. Unfortunately the test suite also requires the tcl bindings, so I can't fix the error.